St Johnstone pair Chris Millar and Tam Scobbie have both been ruled out of Saturday's lunchtime encounter with Premiership champions Celtic.

Midfielder Millar has a groin tear and faces a short-term lay-off while Scobbie will be missing for three to four weeks with a knee injury.

On a more positive note, Tommy Wright has brought in former Aberdeen and Ross County defender Richard Foster and he goes straight into the matchday squad. 

Ally Gilchrist (groin), Dave Mackay (hip), Michael Coulson (thigh) and Keith Watson (thigh) are still out but the latter two are due to return to training next week.

Wright, who went to Celtic Park to watch Celtic against Hapoel Beer Sheva on Wednesday, told The Courier: "It was a good opportunity to see them and they were excellent, particularly first-half. I saw enough to know how tough it is going to be, but Saturday is a different game.

"We know from experience where Celtic's strengths lie and that is the same with every team we play. You have to make sure you stay in the game and look to cause them a few problems."

Patrick Roberts is back in contention for Celtic's visit to McDiarmid Park.

The Hoops winger had begun the season in encouraging fashion before suffering a hamstring injury against Astana in the Champions League qualifying second leg.

He has since made a quicker than expected recovery but may be kept on the bench as Brendan Rodgers keeps a weather eye on the Champions League play-off second leg in Beersheba next Tuesday.

There were no other causalties from Wednesday's electric evening at Celtic Park and new signing Dorus de Vries has trained this week after recovering from a knock to his ankle.

Long-term absentee defender Jozo Simunovic continues his recovery from a knee problem.

Rodgers said of his compatriot Wright: He said: "I don't know Tommy that well, I have spoken to him a number of times over the phone. I don't think he gets the credit for the job that he has done.

"I always look at fellow countrymen him like him, Neil [Lennon], Michael [O'Neill] and I like to see them do well and I think he has done a good job at St Johnstone."