Last Updated: 01/04/12 3:38pm
Craig fires in a shot but it's blocked and that's the final act of the match. Celtic have taken another step towards the title with a deserved victory but St Johnstone certainly weren't overawed and emerge with plenty of credit if not anything to show for it.
Great tackle from Mulgrew down in the corner to halt Oyenuga. Sheridan then clips a ball over the top for the sub but he can't do anything constructive with it and Celtic bring it clear.
We're into three minutes of added time. Mulgrew's curling free-kick is gathered by Mannus diving over to his left.
Brown curls a cross into the St Johnstone box which bounces out to Blackman on the left. His cutback is easily collected by Mannus at the front post.
St Johnstone win it back and Croft slides in Sandaza down the right. His cross is palmed into the path of Craig by Forster but his right-footed shot sails over the crossbar. Should have done much better there.
Free-kick to St Johnstone fairly central around 30 yards out as Croft is fouled. He did actually manage to slide the ball through to Craig but when his shot was blocked, the referee pulled it back.
Samaras spins past Wright down the right flank but McCracken reads the danger well and gets across quickly to slide it behind for a corner.
Meandering towards the conclusion a bit now. Forster smacks a long ball downfield but it bounces straight through to Mannus.
Craig curls the ball into the Celtic box but Mulgrew heads clear. Maybury sends it back into the area but it bounces harmlessly through for Forster.
Mulgrew penalised for a foul on Sandaza. Looked to be a slightly delayed reaction from the striker, but it was definitely a foul.
Samaras is baulked by McCracken as he controls a long ball forward but the referee sees nothing wrong, much to the Greek striker's annoyance.
Bit of blood coming from Wright's nose it seems. I'd wager it's not the first time that's been the case in his career.
Wright's down and needs a bit of treatment. Looks like he caught a knee in the face from Hooper as they both challenged for a bouncing ball.
Craig tries to slip Sandaza in behind but Rogne is alert to the danger and turns it away for a throw-in. Croft then whips a cross in but Craig is penalised for a clear push.
The referee comes over to see his assistant on the nearside and books Craig for something he's said. Not advocating whatever he said, but he looked to have a point - Commons came right through him after he knocked the ball away.
OWN GOAL - MILLAR. Heartbreak for St Johnstone. They thought there was a foul in backplay but Celtic press on forward and Samaras sends a good ball in from the right which Millar turns past his own goalkeeper.
Ball bobbles around the Celtic box with Wright prominent until Rogne clears at the second attempt. Another corner for St Johnstone, though.
Great response from St Johnstone. Croft whips a cross in from the right which Matthews has to slide behind for a corner with Craig poised at the back post.
Just caught a replay - looks a penalty to me. Sandaza got a touch to the ball before Loovens brought him down.
St Johnstone claiming for a penalty now as Sandaza hits the deck in the Celtic box. Again, referee Salmond waves it away. I'd like to see that one again though - looked a decent claim at first glance.
GOAL - SAMARAS. If Samaras was disappointed not to get the penalty, it doe't last long. Commons' delivery from a free-kick earnt by the Greek striker is right onto the head of Samaras and he heads powerfully into the bottom corner.
Sandaza has the run of the Celtic half but has just strayed offside before he sets off. The free-kick is worked to Samaras, who goes down under pressure from McCracken but the referee is unimpressed by penalty claims.
Terrier-like from Croft as he forces Celtic back from around 20 yards out to halfway. He's put in a shift today that's for sure.
This Commons corner is headed clear at the front post and when it drifts out for a Celtic throw, they make their change.
Decent build-up play by Celtic once again and Matthews slides it to Brown on the edge of the box. He takes a touch and fires in a curling shot which is deflected behind for a corner. That's worked back to taker Commons and his cross/shot is tipped over by Mannus as it dips towards goal.
Brown goes down on his haunches clutching his face after an aerial challenge with Morris but somehow the decision goes to St Johnstone. Baffled by that one I've got to say - Morris clearly caught Brown in the face, albeit unintentionally, with his arm.
Sheridan catches Ledley in possession on halfway and again Celtic fans groan as a collective. Patient build-up play from St Johnstone and the ball eventually breaks for Millar but his long-range shot is never troubling Forster.
Samaras clips a decent ball in from the right which Commons fancies his chances of heading goalwards but Mackay is there in the nick of time to powerfully head clear.
Another decent ball in from Craig on the left but Forster manages to palm it away from immediate danger. It drops to Wright at the back post but he can't do anything with it and Forster gathers.
Physio is on so Rogne won't be able to assist with the defending of this corner. Subs being warmed up but not yet clear if Rogne will be able to continue.
Corner to St Johnstone but of more concern to Celtic will be the fact Rogne is down holding his left leg. Looks like he's turned his ankle as he landed after heading the ball out for the corner.
Mulgrew tries to slide the ball down the left to Samaras but referee Salmond blocks it accidentally and then awards a free-kick to Celtic as Brown commits a foul. Brown is seething and lets the referee know about it, earning himself a ticking-off.
Mulgrew and Sandaza tangle out on the Celtic left and the referee gives the free-kick to the Bhoys. Sandaza's not too happy but he'll have to retreat the 10 yards.
Stokes does well to get the ball in from the left into the St Johnstone six-yard box but Mannus manages to gather before Hooper can turn it in at the back post.
Another great ball in from Craig which Sandaza leaps to meet but his header just loops over the crossbar and lands on the roof of the net. Celtic need to get themselves going here.
Sandaza does well to draw a free-kick inside the Celtic half. Decent chance to get the ball into the box.
Craig twists and turns down the left and whips a great ball in but it's just a shade in front of Sheridan and Forster gathers well.
Best chance of the game so far as Mackay clips a lovely ball in for Sheridan from the right. He's across the front of his marker but can't divert his header on target. Should have done better.
Commons whips the ball in but it's headed clear and St Johnstone look to break down the left. Poor ball, though, and Sandaza can't get to it.
First free-kick of the half goes to Celtic as Millar is penalised for a foul on Brown around 35 yards from goal. He looks bemused.
Lennon has told Sky his Celtic players need to 'quicken it up' after being a bit 'pedestrian' before the break. He wants to see more intensity.
Let me know your thoughts on the first half - and how you see the second 45 unfolding - with an email to email@example.com or with a tweet @reecekillworth
Celtic remain odds-on favourites with Sky Bet - they're 4/7 shots for the victory. St Johnstone have been trimmed slightly to 7s with the draw now a 2/1 chance.
Croft caught offside as St Johnstone press and that's the last act of the half with just seconds of added time played. Been some decent build-up play from both teams thus far but both lacking the necessary quality in the final third just yet.
Commons' free-kick is dealt with shakily by Mannus. He flaps rather and the ball falls enticingly for Mulgrew. His apshot is headed off the line by the perfectly-placed Wright and Stokes' follow-up is blocked as St Johnstone get bodies in the way. Samaras thought he had a decent shout for a penalty as he went in for the initial ball in but play continues.
Commons whips the corner in and it's cleared out to the right. Another cross comes in but once again it's cleared. Croft leaps with Ledley as the ball drops and catches him the face with his leading arm. He's booked.
Corner comes to nothing and Celtic break forward. Stokes twists to get a shot away but it's blocked behind for a corner.
Croft cuts a cross back from the right and it slides all the way across to Craig. Lustig closes him down quickly and blocks the shot straight behind for a corner.
More groans - albeit less audible - as another Celtic move breaks down around 30 yards from the St Johnstone goal.
Commons goes over Morris' outstretched leg in the centre circle and the referee obliges with the free-kick.
Decent ball in from Lustig from the right but there's no-one in the box taking a chance and Wright is able to leave it and let it drift out of play.
Not sure what his specific complaint is, but Lennon is getting a little agitated on the touchline - he's had a couple of chats with the fourth official.
Samaras controls a long diagonal ball forward and looks to turn and run at the St Johnstone defence, but he handled it and the referee pulls it back.
Once again, a heavy touch prevents a decent chance as Samaras' control lets him down inside the St Johnstone box.
Sheridan is in acres of space as a ball forward from Wright heads for him, but it's pretty clear why as he leaves it alone. He was yards offside as he headed back towards halfway.
First sign of frustration from the home fans as a Stokes lay-off towards Hooper goes around 10 yards away from the planned destination. Groans ring around the stadium.
Commons tries to spring Joe Ledley over the top but it's too heavy and Mannus is able to clear comfortably. Some decent build-up play from both teams so far but final ball lacking in the main.
Craig whips an angled ball in from the left but once again the delivery is poor and it sails behind for a goal-kick.
MacKay tries to send Sandaza clear down the right but the striker has his back to goal as the ball is played and it drifts back to Forster.
Samaras tries to play in Stokes down the inside right channel but the ball is much to heavy and slides behind.
Decent build-up play from St Johnstone as Sandaza and Sheridan link up but the ball in is well cleared by Loovens and Celtic look to break now.
Samaras tries to clip a ball in for Hooper but they're not on the same wavelength and it's a comfortable clearance for McCracken to make.
Craig curls in the free-kick but it's pretty comfortable for Forster, though he does opt to punch clear rather than hold. St Johnstone do nothing with the subsequent throw, though, so he's vindicated in that decision.
Free-kick to St Johnstone as Croft tries to skip through around 30 yards out. Clear foul by Brown. Croft tried to keep his feet but the advantage wa't there so a definite free-kick.
Great chance for Celtic to break the deadlock. Stokes slides a lovely ball through to Commons down the inside left channel but his left-foot shot curls wide of the post.
Mulgrew powers out of defence and tries to make ground towards the St Johnstone area but Chris Millar gets the block in. Saints midfielders getting through plenty of work.
Stokes turns nicely around 30 yards from St Johnstone but the terriers in midfield soon close him down and the ball is cleared.
Hooper and Stokes link down the inside right channel with the latter springing the former into space and through. He tries to loft a shot over Mannus but just doe't get enough on it. Celtic appeal for a free-kick as Stokes was fouled as he laid the ball on for his team-mate but the advantage was clearly there for Hooper so I think he got that right.
As the clock ticks to the 19th minute, Parkhead rises in applause for Petrov with the Celtic bench - including several of Petrov's former team-mates, of course - joining in.
They certainly get that and David McCracken climbs to meet it at the back post but his header is more a looping effort and Fraser Forster gathers pretty comfortably.
Croft and Sandaza link well down the right with the latter forcing a corner for St Johnstone. Need better delivery this time.
Mulgrew's throw is half-cleared to Commons on the edge of the box but his apshot is always flying over the crossbar.
Samaras tries to jink into the St Johnstone box down the left but has to be content with a throw-in.
Cillian Sheridan and Craig try to link down the St Johnstone left but Lusting is in sharply to halt their progress.
Mannus races out to the edge of his area to grab the ball as Charlie Mulgrew tries to spring the St Johnstone offside trap down the Celtic left. Open game so far - it's good to watch.
St Johnstone knocking the ball around nicely until Frazer Wright overhits his ball out towards Sandaza on the right. Lee Croft then whips a ball in from that side but it drifts out again for a Celtic throw.
Wasteful from St Johnstone as the ball is whipped in and drifts out of play right on the other side for a Celtic throw-in.
Great overrule from the referee as his assistant over on the right awards Celtic a goalkick when Thomas Rogne clearly got a flick header on a long ball down the right. Corner.
Francisco Sandaza's first real involvement is out on the left as he spins away from Glenn Loovens and cuts inside and whips a cross over. The ball is whipped in and though it's a bit heavy, it's worked back to Morris but his shot is always wide.
Samaras is really up for this one today. This time he flicks the ball over David MacKay's head and lofts a cross over but Stokes can't get enough of a header on it and it's a comfortable save for Mannus.
Brown tries to slide in Kris Commons down the inside-right channel but Jody Morris is there to halt the attack. It's at the expense of a Celtic throw, though.
Good working back from Samaras as he twice intervenes to nick the ball back and set Celtic on the attack.
Confusion as referee Salmond halts play in the Celtic half. The Bhoys think Alan Maybury is penalised, St Johnstone reckon it's Scott Brown. The referee awards a dropball.
Anthony Stokes whips the free-kick in but in truth it's always sailing comfortably over Alan Mannus' crossbar.
Powerful early run from Georgios Samaras down the middle straight from kick-off and he's only halted seven or so yards outside of the box by a trip from Liam Craig. Would surely have been a booking had it come later in the game but Craig escapes.
Here goes. St Johnstone: Mannus, MacKay, Wright, McCracken, Maybury, Croft, Millar, Morris, Craig, Sheridan, Sandaza. Subs: Enckelman, Anderson, Moon, Robertson, Oyenuga, Moffat, Mitchell.
Lomas chuckles when asked if he's thinking about third place and insists he's focusing simply on one game at a time at the moment. He says Saints must be at their 'maximum and maybe ride our luck a little' to get a result today.
Celtic players have warmed up with shirts with 'Petrov 19' on the back after the news on Friday that former Bhoy Stiliyan Petrov has been diagnosed with acute leukaemia. Lennon says he spoke to the Bulgarian yesterday.
Neil Lennon praises Steve Lomas in his pre-match interview with Sky, saying he's been 'excellent' since taking charge and that St Johnstone have been a 'revelation' this season. Says some of his players have looked 'leggy' and 'mentally tired' lately, hence changes to the starting XI here.
Celtic team: Forster; Lustig, Rogne, Loovens, Mulgrew; Commons, Brown, Ledley, Samaras; Stokes, Hooper. Subs: Zaluska, Matthews, Izaguirre, K Wilson, Ki, Blackman, McGeouch.
Another lovely day at Parkhead. St Johnstone, of course, are the only visiting Scottish team to have won here this season - a 1-0 SPL win back in August.
No prizes for guessing who Sky Bet see as the favourites for this one. Celtic go off 4/11 favourites with St Johnstone 8/1 shots and the draw available at 7/2.
Afternoon all. We're at Parkhead for the day's opening SPL match with leaders Celtic facing fifth-placed St Johnstone. Rangers' victory over Motherwell yesterday means the Bhoys can't clinch the title today but it's surely only a case of delaying the inevitable given Neil Lennon's men have a 15-point lead at the top going into today's game. If you want to get involved, you can email me on firstname.lastname@example.org or you can tweet me @reecekillworth