All eyes were on the touchline as the combustible managers faced off, with Manchester City's latest win leaving United eight points off the Premier League summit as pressure mounted on Conte just months after leading the Blues to the title.

The Italian twice got the better of Mourinho at Stamford Bridge last season and made it a hat-trick in a tense encounter on Sunday, with Morata's fine header giving Chelsea a deserved 1-0 win against second-placed United.

It looked like the Spain international would instead be wearing red until Mourinho completed a summer move for Romelu Lukaku, whose goalless streak stretched to a seventh match as the Chelsea striker brought his scoreless run to a timely halt.

Having seen an early Phil Jones own goal ruled out because of his foul, Morata capitalised on lacklustre United defending to superbly head home Cesar Azpilicueta's cross in the 55th minute.

It was no less than Chelsea deserved as they pressed the issue against an increasingly ramshackle United, although Marcus Rashford and Marouane Fellaini went close to snatching a fortuitous point as the clock wound down.