Young kicks out at Sterling and gets a deserved yellow card for it. That was pure frustration.
We're into four minutes of stoppage time at the end of the game. Mourinho is upset about something — although it is unclear whether or not it's that.
Bernardo takes a tumble in the penalty area, but Oliver is unmoved.
SAVE! De Bruyne finds Bernardo with a long ball and he draws a good save from de Gea at the near post.
FULL-TIME: MANCHESTER UNITED 1-2 MANCHESTER CITY. City take an 11-point lead at the summit of the Premier League! Otamendi's second half goal has won the game for them after they went into the break at 1-1! Guardiola gets another one over Mourinho.
Sané is substituted off and he takes his time as he leaves the field. Bernardo Silva is on.
A fantastic piece of skill near the corner flag from Sané wins the visitors a corner. He does superbly to get the ball off a United foot.
DOUBLE SAVE! Ederson has just kept City's lead with an astonishing double save, denying first Lukaku from close-range and then Mata on the follow-up.
Matic threads the ball to Mata, who is adjudged to be offside. That's a tight call.
Mata comes on and Herrera is the man to make way.
Ibrahimovic gives away a free-kick for a foul on Otamendi in the air.
Herrera goes down looking for a penalty, but instead, Oliver awards a free-kick in favour of Otamendi and against him. The United midfielder is booked and he is absolutely livid. His reaction to the decision is aggressive and over the top.
SAVE! The chance is created by a long ball to Rashford, who gets away from Delph and into the box before firing the ball in the direction of Ederson, who makes the save. Meanwhile, Ibrahimovic comes on for United in place of Lingard.
Silva picks up a yellow card. It looks as if it's probably for his foul on Herrera.
Rashford goes for goal, but he fails to get enough dip on his free-kick and fires over the bar.
SAVE! De Bruyne glides through and goes for a low shot from just outside the box. A strong hand from de Gea keeps it out.
Sterling makes a cynical foul from behind on Martial and concedes a free-kick in a dangerous area.
City are still creating chances on attack. De Bruyne fires the ball straight into Matic, his fellow former Chelsea man.
City give the ball away cheaply as Otamendi passes straight to Matic. United quickly work the ball to Lukaku, who fires into the Stretford End.
Rashford picks up a yellow card for dissent after throwing the ball into the ground after a decision went against him.
Manchester United look absolutely deflated after going behind for a second time. City are still controlling the game.
Mangala looks set to come on for City, who are knocking the ball about patiently now.
Jesus is the man to make way for Pep Guardiola's side as Mangala comes on. He takes his time getting off the field.
GOAL! Herrera gives away a free-kick in a promising position for City. Silva whips the ball in. Lukaku makes a hash of clearing it and Otamedi seizes the chance, slotting home after the ball bounces to him to put his side in front. 1-2.
United enjoy a good spell on attack, but City get the ball after Otamendi cuts out Rashford's cross and they look to break. It doesn't lead anywhere, though.
De Bruyne slips a clever ball through for Silva, but he can't tee up a team-mate for the shot.
Manchester City get the second half underway.
Gundogan is on for Kompany and Lindelof for Rojo, who picked up an injury in the first half and might not have recovered fully.
Rashford whips in a corner and it goes out to Matic, but he can't quite control it.
We're into four minutes of stoppage time at the end of the first half.
GOAL! United equalise following a horror show at the back for City! They fail to deal with a cross. Otamendi misses it and Delph fails to clear. It falls to Rashford and he equalises! 1-1.
HALF-TIME: MANCHESTER UNITED 1-1 MANCHESTER CITY. The visitors have had the better of the derby at Old Trafford so far, but following Silva's opener, they allowed Rashford to equalise. It's all square at the break.
GOAL! Following the ensuing corner, Silva turns the ball home! It bounces to him following a tussle between Lukaku and Otamendi for the first ball. He tucks it home and City lead! 0-1.
SAVE! Sané forces a fantastic acrobatic stop from de Gea at the near post.
Silva and Sterling almost combine with a clever one-two, but the final pass is slightly overhit and it's cut out.
Play is back underway and Rojo and Silva appear fine to continue.
Rojo gets a yellow card for a clumsy aerial challenge on Silva. The foul prompts Guardiola to have a word with Mourinho on the touchline. Who wouldn't love to listen in to that conversation? Both players went down following the collision.
It's clear that these teams aren't the best of friends. Rojo and Sterling are having a heated argument — not the first of the game.
Lingard gets the ball in the net, but only after he fouls Otamendi on United's right. The goal doesn't count.
Otamendi goes for goal, but he fires well over. City still look most likely to score out of the two sides.
Manchester United have weathered the City storm and look slightly more assured now than they did a few minutes ago.
Guardiola is in dialogue with Mikel Arteta. It seems an intense conversation.
Fernandinho goes for another long-range strike, but fires high into the Stretford End.
No booking is administered to the Belgian for that hefty challenge.
Kompany goes in hard on Herrera. United want a yellow card for that.
Manchester City are still in the driving seat, with United struggling to get out of their own half.
Jesus goes to ground on attack inside the penalty area, but gets nothing for it.
It's unclear whether Rashford was going for a cross or an audacious long-range shot, but Ederson gathers and holds onto the ball either way.
Manchester City are in the ascendancy early on. De Gea has made a couple of comfortable saves in the last minute, denying Sterling and Jesus.
A corner deflects off Matic into the arms of his own keeper. The former Chelsea man was lucky. That could have gone anywhere off him. Moments ago, Herrera was perhaps fortunate not to give away a penalty for wrestling with a City man in the box.
Matic catches Walker and he goes down rather easily. The former Tottenham man looks as if he wants a booking. The Serb is bemused by the awarding of a free-kick.
Fernandinho goes for the shot at goal, but hits it straight into Jesus.
Sterling plays a clever pass into the path of Jesus. If he was able to control it upon receipt, it would have been a fantastic chance from close range, but it's gone away from him.
It's been a cagey start to this encounter. There have been plenty of early fouls, but no clear chances so far.
Young goes for the long ball, but overhits it. It goes all the way to Ederson.
Kyle Walker picks up an early yellow card for a late challenge on Herrera. It looked as if he was trying to kick the ball, but instead caught the midfielder.
The match is underway at last. Referee Michael Oliver blows his whistle to start it off.
Hello and welcome to this top-of-the-table clash in the Premier League. England's most historically successful club, Manchester United, hosts it's most formidable team in the present moment, Manchester City. This promises to be a classic Manchester derby.
Manchester United starting XI: de Gea, Valencia (C), Smalling, Rojo, Young, Matic, Herrera, Rashford, Lingard, Martial, Lukaku.
Manchester United subs: Romero, Lindelof, Jones, Shaw, McTominay, Mata, Ibrahimovic.
Manchester City starting XI: Ederson, Walker, Otamendi, Kompany (C), Delph, Fernandinho, de Bruyne, Silva, Sterling, Sane, Jesus.
Manchester City subs: Bravo, Zinchenko, Gundogan, Bernardo, Mangala, Danilo, Aguero.
United are eight points behind City at the top of the table. With Chelsea, Liverpool and Arsenal all having just dropped points, these two are clear favourites in the title fight. Should City win here, it will be tough for even United to fight back.
The teams are out of the tunnel and a rocking Old Trafford is nearly set to witness an eagerly-anticipated derby.
Mourinho and Guardiola shake hands. On the surface, it seems relatively warm, but the old foes will both be starving for a win today.
Manchester City XI: Ederson Moraes, Delph, Otamendi, Walker, Kompany, Fernandinho, De Bruyne, Silva, Sterling, Leroy Sane, Gabriel Jesus
Manchester City Subs: Bravo, Agüero, Mangala, Gündogan, Danilo, Bernardo Silva, Zinchenko
Manchester United XI: de Gea, Young, Antonio Valencia, Smalling, Rojo, Lingard, Martial, Rashford, Ander Herrera, Matic, Lukaku
Manchester United Subs: Jones, Shaw, Victor Lindelöf, Ibrahimovic, McTominay, Romero, Mata