De Gea is receiving medical attention.
Boyhood Manchester United fan Odion Ighalo replaces Martial for the Red Devils.
We're into five minutes of stoppage time, so a comeback is possible, albeit not easy.
Fernandes has made a superb start to life at Manchester United. He is off for Dalot now though, receiving a rambunctious reception as he leaves the pitch.
FULL-TIME: CHELSEA 0-2 MANCHESTER UNITED. Manchester United do the league double over Chelsea for the first time in the Premier League era. Goals came from Maguire and Martial. Chelsea had two goals disallowed.
POST! Mount's free-kick strikes the near post. Agonisingly close!
Pedro lets fly after some pinball in the box. It's blocked behind for a second straight corner.
This has been a hot tempered game due to two crucial VAR decisions which could cost Chelsea in the long run.
United are content to run the clock down at this stage.
Pereira is on in place of Daniel James for United.
Wan-Bissaka picks up a yellow card following an off-the-ball confrontation with Azpilicueta.
GOAL DISALLOWED! A lovely cross from Mount finds Giroud and he heads home for what seems set to be a crucial goal, but the goals is ruled out for offside! It's such a tight call too!
Manchester United youngster Williams has picked up a yellow card following his challenge on Willian.
James' free-kick attempt for Villa goes wide of the target.
Fernandes nearly sets Maguire up for another goal from a free-kick. Azpiliueta is forced to intervene.
Giroud comes on in place of Batshuayi, who looked lively but did not make ideal decisions in front of goal.
GOAL, UNITED, MAGUIRE! 0-2: Bruno Fernandes finds Maguire from the corner and the captain scores his first Premier League goal for the Red Devils!
POST! A thunderous Fernandes strikes from the free-kick cannons of the post!
Fred takes Pedro off the ball and wins a free-kick.
Manchester United lead away from home at the hour mark, but that lead is under threat. Chelsea are pushing forward for an equaliser.
Fred picks up a yellow card, as does Zouma for his challenge.
Tempers are flaring between the sides with Martial on the deck.
GOAL DISALLOWED! 0-1: Azpilicueta's push on Williams has denied Chelsea and Zouma a goal.
GOAL, CHELSEA, ZOUMA! 1-1: Zouma strikes home from a corner to put Chelsea back level! We're going upstairs to look for a push.
CHANCE! Azpilicueta's cross is blocked, as is Pedro's effort.
Mount produces a stunning save from de Gea, but the whistle had gone earlier in any case.
Chelsea are on the ball, but they're struggling to break down this solid United defence.
Willian hits the ball across the face of goal and out for a United throw-in. Frank Lampard appears livid with his team.
Bruno Fernandes looks to play Martial in on goal, but Chelsea's James is there to sweep up the danger.
Rudiger picks up a yellow card for blocking off the run of Bruno Fernandes.
KICK-OFF! The second half is underway. Chelsea have brought Zouma on in place of Christensen, who appears to have succumbed to the injury sustained in the first half.
GOAL, UNITED, MARTIAL! 0-1: Wan-Bissaka shakes off Willian to make space for the cross, picking out Martial with a peach of a ball. The Frenchman nods the ball home effortlessly. United lead at Stamford Bridge!
We're into a minimum of three added minutes at the end of the half.
CHANCE! Batshuayi hits United on the break and plays a superb pass inside to Pedro, who finds Batshuayi, who fires wide of goal! He's done plenty right in this game, but not found the back of the net.
HALF-TIME: CHELSEA 0-1 MANCHESTER UNITED: The Red Devils lead at the break thanks to a superb Martial header — the first effort on target all game.
Christensen appears to have been caught in the face by Martial. He is receiving medical attention. In all likelihood, he will be alright to continue.
Chelsea move forward again, but Azpilicueta's cross from the left is blocked by Wan-Bissaka.
Great run from Shaw on United's left, but the cross (if it is a cross) at the end of it is terrible. He skies the ball behind for a goal-kick.
Martial plays a give-and-go off a team-mate on United's left flank before driving into the box and firing off target. Good run from the Frenchman.
Willian goes down on the edge of the penalty area, but the decision is a yellow card for diving! It would have been a free-kick had the call gone his way against Fernandes.
Azpilicueta breaks through inside the box for Chelsea, but Bailly takes the ball off him.
Bruno Fernandes tries a trademark long-range strike, but it's a poor effort and he fires well wide.
Chelsea look to pass their way out from the back. It looks rather nervy, with Manchester United seeking to force an error with their high press.
CHANCE! Mount cuts back for Batshuayi now. This one, he should put away from inside the box. However, he slides his shot just wide of the post!
Willian finds Batshuayi with a cut-back, but the Belgian frontman is unable to control the ball and get a close-range shot away.
Batshuayi gives Maguire a bit of a push and the Manchester United defender appears to kick out. Anthony Taylor goes to VAR and the ruling is that there will be no red card for violent conduct.
A promising counter-attack from Chelsea ends with Pedro colliding with Fred. The Spaniard goes down, but Anthony Taylor declines to award a free-kick within shooting range.
Batshuayi plays a one-two off Jorginho, but then slips to the amusement of some (presumably Manchester United) supporters.
Daniel James looks to pick Martial out at the far post with a cross, but Rudiger checks the latter's run and the ball goes safely behind.
Fred and Bruno Fernandes exchange passes before the former has a shot deflected wide for a corner. Frank Lampard uses the opportunity to bring Mount on for Kanté.
Kanté has picked up an early injury and looks set to be replaced by Mason Mount, who is stripping down and preparing for battle.
Willian receives the pass from Pedro, cuts inside from the right, and has a crack at goal. He is just unable to curl the ball inside the far post. Chelsea look the more threatening of the two sides.
Chelsea look comfortable on the ball. A patient build-up ends with James trying one from long range. Good low effort, but just wide of de Gea's right-hand post.
Pedro wins the ball to put Chelsea on the attack, but Kovacic sees his pass intercepted and it all comes to nothing. Nervy from United early on.
KICK-OFF! Manchester United get the game underway at Stamford Bridge with new signing Bruno Fernandes kicking off. Anthony Taylor is tonight's referee.
Hello and welcome to our live coverage of this Premier League clash between two Champions League-chasing teams in Chelsea and Manchester United at Stamford Bridge.
CHELSEA XI: Caballero, James, Christensen, Rudiger, Azpilicueta (c), Kanté, Jorginho, Kovacic, Willian, Batshuayi, Pedro. SUBS: Kepa, Tomori, Zouma, Alonso, Barkley, Mount, Giroud.
MUFC XI: de Gea, Wan-Bissaka, Bailly, Maguire (c), Shaw, Williams, Fred, Matic, B. Fernandes, James, Martial. SUBS: Romero, Dalot, Jones, Pereira, Mata, Greenwood, Ighalo.
Manchester United have often struggled against Chelsea in the last two decades. However, they have won three and drawn two of their last five games against the Blues. Ole Gunnar Solskjaer has beaten Frank Lampard in the league and League Cup.
The teams head out onto the field to face the music at Stamford Bridge. Make no mistake about it — this game is absolutely crucial for both sides.
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