Last Updated: 23/01/15 10:03pm
CHANCE! Januzaj wriggles between two challenges on the left edge of the area. His cross shot is punched clear by Dunn but only to Di Maria who fires a strong left foot volley at goal but the 'keeper gets down quickly and make a save! Cambridge clear!
SAVE! Januzaj twists and turns down the left, beats his man and but fires a shot straight at Dunn, who takes his time with the clearance. Can Cambridge hold on?!
Donaldson's free-kick is far too straight and De Gea takes an easy catch. Wasted opportunity for the hosts.
It's Cambridge that are on the front foot at the moment as Chadwick tries to orchestrate an attack through the middle. Carrick fouls McGeehan and Cambridge have a free-kick 35 yards out! The big men are coming up!
Blind breaks up play and sends Di Maria away on the left. His cross causes a bit of problems in the Cambridge box but Falcao heads wide from 10 yards.
De Gea shows his steel from the corner as he punches the ball away under pressure from about three Cambridge attackers!
Donaldson breaks down the Man Utd left and fires a wonderful cross that Jones heads behind for a corner!
Januzaj digs out a wonderful cross from the left flank and it flies across the face of the goal. Where was Van Persie and Falcao?
Chadwick plays a loose pass in midfield and Di Maria starts another United counter. Cambridge get numbers back and clear.
Jones once again gives away cheap possession inside his own half and Cambridge are now on the attack.
United are knocking the ball about with much more ease in this second half but Cambridge are dealing with their pressure - 13 minutes left!
Donaldson gives possession away cheaply by his corner flag. Herrera picks out Valencia who drives down the right channel into the box but Nelson takes advantage of a poor touch and clears.
CHANCE! Di Maria picks out the run of Van Persie in behind Nelson but the striker fires over from eight yards!
Jones drives forward from centre half and fires a shot from 25 yards. The ball sails over Dunn's crossbar.
Oh dear. Valencia has space down the right but allows the ball to slip under his foot and out for a throw in under no pressure.
The yellow card is the last bit of action supplied by Wilson. He is replaced by Van Persie. Herrera is also on for Fellaini.
Cambridge are struggling to get out of their half. Donaldson sends the ball down the right but Elliot is ushered away by Jones.
CLOSE! Falcao is released through on goal by Carrick and his first touch sets up a chance. He looks certain to score but Dunn gets a hand to the ball and somehow diverts it over the crossbar. Best chance of the game so far.
PENALTY APPEAL? McGeehan curls a fine ball looking for Elliot at the back post. He is grappling with Valencia but the ball sails out of play. Half hearted appeals from the home crowd but nothing given by Chris Foy.
United switch the play but Valencia and Fellaini get in a right muddle and the ball runs tamely out of play.
The left flank again is used as United's main source of danger. Blind flicks a ball inside to Januzaj, who drives into the area but is denied by a brilliant tackle by Nelson.
Pressure starting to grow here on the hosts. Blind links up well with Wilson down the right and win a corner. Jones to take...
Di Maria finds space on the left flank and floats a good ball into the area looking for Fellaini but Cambridge get enough men in the area to deal with situation.
SAVE! Valencia makes good ground down the right and sends over a cross that finds Januzaj at the back post. He shifts the ball onto his right but fires a shot straight at the 'keeper.
Rojo decides to go it alone down the left after Cambridge snuffed out all his options. He makes good ground but his cross is straight at the 'keeper.
WIDE! Di Maria gets the right shape on the ball but gets the trajectory all wrong as the ball goes wide and high of the bar.
Foul on Falcao by Coulson 30 yards from goal. Di Maria is lining this one up. Just right of centre...
Blind sloppily gives the ball to McGeehan 30 yards from goal but Donaldson can't make the most of the opportunity down the right as Rojo clears.
Di Maria again finds a bit of space 30 yards out and decides to shoot rather than find Wilson or Falcao. The shot is a poor one though and deflects through to Dunn.
Almost a carbon copy of the last clearance as this time Blind has to defend strongly at the back post to deny a rampaging Donaldson. The ball comes off the United man but a goal kick is given.
Donaldson overlaps Tait on the right flank and digs a good cross out. Kaikai is lurking at the back post but Valencia clears with a strong and important header.
Januzaj finds space in a central area and tries to play Di Maria in behind Tait but the Cambridge full-back stays strong and clears with a solid sliding tackle.
SAVE! Januzaj and Blind work an opening down the left. The ball finds Di Maria on the edge of the box, who fires a tame shot straight at Dunn. The 'keeper gathers on the second attempt but no United attacker was closing in.
CHANCE! From the corner, Nelson beats Jones in the air inside the six yard box and the goal bound header is blocked by Coulson on the line. The ball pops back up to Coulson who somehow heads over from two yards! Big let off for United.
Kaikai slips away from Fellaini down the left flank. The midfielder makes 40 yards and wins a corner off the big Man Utd midfielder.
Wilson gives the ball away on half way and McGeehan bursts towards the Man Utd box. Elliot makes a move to come short but McGeehan plays one in behind and the chance is wasted.
Donaldson again drifts inside off his wing and beats Blind and Carrick. He tries to find Kaikai on the edge of the box but he over hits the pass.
Di Maria finds space 30 yards from goal and unleashes a half volley at goal. The ball clears the crossbar and the stand behind the goal!
SAVE! Valencia makes waves down the right and finds a good cross that is cleared by Nelson. Januzaj is waiting on the edge of the box but fires a tame right foot shot straight at the 'keeper.
Under no pressure Jones sloppily gives the ball away 30 yards from his own goal. Donaldson picks up the ball but his touch lets him down when nearly through on goal. Rojo clears.
McGeehan sends Elliot on his way down the right with a fine ball but Rojo stands tall and mops up the danger. Cambridge recycle possesion though and Elliot heads a Donaldson cross miles wide from the edge of the box.
BLOCK! Di Maria glides to the corner of the Cambridge box and slides a ball to Falcao but his shot is blocked away for a corner by Taylor.
Donaldson beats Blind with a fine nutmeg on half-way and is then crunched by Rojo. Blind is then fouled by Tait on the touchline. Spicy stuff under the floodlights here.
CHANCE! Donaldson's free kick is cleared for a corner by Jones. The Cambridge man whips another ball in and Hughes loses his marker but can only volley wide of the post from 12 yards.
SAVE! Januzaj threads a great ball through to Blind down the left, he cuts inside his full-back and fires a shot from 12 yards which is pushed away by Dunn.
Kaikai shows a nice turn of pace to drive into the Man Utd box but is stopped by a solid tackle by Jones. He had to get that one right.
Donaldson floats a wonderful ball into the box and Elliot gets a run on Fellaini but mistimes his jump and the ball runs behind for a goal kick.
Fellaini fouls McGeehan 35 yards from goal on the left flank. Here's a chance to get the ball into the box....
Nelson lets Di Maria know he's in a game and executes a fine tackle on the midfielder. Di Maria then finds space on the left but runs the ball out of play. Nervy.
Champion signals Cambridge's early intent and launches a ball towards Elliot. He wins the ball and forces an early throw in. The crowd respond like a goal has gone in!
The teams are out and the atmosphere is electric. A huge night for these Cambridge players and fans alike.
We're just five minutes away from kick-off here. Feels like a special night at the Abbey Stadium. Is the magic of the FA Cup in the air?
@Nelnelzz is another one going for a routine away win: 'I go for a 3-1 to United 1-1 at HT but United to score 2 in the second half to win it.' Come on people, can anyone see a shock?
@BigManRam85 says 'Manchester United still need to find that killer instinct, going for a 4-0 score to the reds!!! #fridayfooty' Nice use of the hashtag. I like.
@NeilPearce has thrown us some chat, he says: 'UTD to win 3-0 with Falcao x 2 and Fellaini to score'
@xrcher has been in touch, welcome sir! He says: 'I think Man United will win 2-0 but think it'll be a little more difficult than they expect!' I tend to agree, Alex.
We've got a bit of time to fill before kick-off (7:55) so let's try some engagement. Got a view on the game? A prediction? Let me know @_LJones_ or @SkyFootball and I may make you famous for 15 minutes.
Team news headlines: the big news is.. a United legend misses out. Yes, Luke Chadwick is only fit enough for the bench for the hosts. Oh, and Wayne Rooney is not in the squad either. Probably rested. LVG will confirm in due course.
Cambridge XI: Dunn, Tait, Taylor, Coulson, Donaldson, Champion, Elliot, Hughes, Nelson, McGeehan, Kaikai.
Man Utd XI: De Gea, Jones, Rojo, Blind, Valencia, Carrick, Fellaini, Januzaj, Di Maria, Wilson, Falcao.
Who's got that Friday feeling then? I have. This fourth round tie should be a cracker. The Abbey Stadium is ready... Are you? The team news is about to drop. I'll go fetch.