United, who had Nemanja Matic sent off for a second bookable offence in injury time, had an early effort from Alexis Sanchez disallowed for offside but soon took command via a scrappy 35th-minute effort from Romelu Lukaku and a superb left-foot volley from Chris Smalling three minutes later.
Chelsea coach Antonio Conte welcomed the pressure other clubs are trying to maintain on his runaway Premier League leaders and said he expected a battle until the season is over.
Manchester United striker Zlatan Ibrahimovic is relishing his time at the Premier League club and is in talks to extend his contract, saying he "never leaves a job unfinished".
The 32-year-old German, who signed for United at the start of last season, has fallen out of favour since manager Jose Mourinho arrived at the club at the start of the current campaign.
Carlo Ancelotti says he would like to return to England's Premier League but the Italian manager with one of the most garlanded records in world football is not interested in taking any new job this season.
News of all that's transpired on and off the football field
Under pressure from the chasing pack and rocked on their heels by a Charlie Adam bolt from the blue, Chelsea showed cool heads to extend their Premier League to seven points on Saturday with a 2-1 home win over Stoke City.
A flash of attacking brilliance from Olivier Giroud and an emphatic header from substitute Alvaro Morata earned Chelsea a 2-0 win over struggling Southampton
Mourinho was also adamant that it was crucial to United's ambitions to keep the 28-year-old Spain international, who has been linked with French champions Paris St Germain.
News of all that's transpired on and off the football field.
World Cup winner Paul Pogba's third minute penalty and a late goal from Luke Shaw gave Manchester United a 2-1 win over Leicester City at Old Trafford in the opening game of the Premier League season on Friday.
Real Madrid goalkeeper Iker Casillas was forced off in the 15th minute of Tuesday's 6-1 Champions League Group B romp at Galatasaray after sustaining a rib injury in a collision with team mate Sergio Ramos.
Jose Mourinho's United side have 62 points and lead the Merseyside club by two with nine game remaining.
Zlatan Ibrahimovic is poised to write the final chapter in a glittering career with Manchester United in England's Premier League and although drama is guaranteed, a happy ending is not.
'Manchester United must always continue their tradition of bringing through players from the youth academy.'
Manchester United suffered their third defeat in eight days as Watford handed Jose Mourinho his worst run as a manager in a decade. Goals from Etienne Capoue, Juan Zuniga and a late penalty from Troy Deeney overwhelmed the visitors, who had levelled with a solitary strike from Marcus Rashford.
An ecstatic home crowd at a noisy and rainy John Smith's Stadium celebrated what was the Yorkshire club's first win over United since 1952 and one which few would doubt they deserved after a passionate display.
Petr Cech helped the Gunners enjoy a rare victory over Jose Mourinho's side on Sunday.
UEFA's FFP rules face likely changes in the wake of the CAS ruling and Mourinho said the system needs to be overhauled if it is to continue to serve its purpose which is to aim to stop clubs running big losses through spending on players.
Romelu Lukaku struck twice as Manchester United returned to winning ways after two successive Premier League losses with a 2-0 victory over Burnley at Turf Moor on Sunday.
Manchester United's troubled season hit a new low on Saturday as Jose Mourinho saw his gamble on introducing a new tactical system backfire with an insipid 3-1 defeat to West Ham United in the Premier League.
Antonio Conte's increasingly fractious relationship with Tottenham Hotspur came to an end with the English Premier League club announcing they had parted ways with the Italian on Sunday.
Manchester United midfielder Paul Pogba played a "big role" in Romelu Lukaku's decision to join the Premier League giants from Everton, the Belgian striker has said.
Swedish striker Zlatan Ibrahimovic said on Thursday he was joining Manchester United, the highest-profile signing to date by new manager Jose Mourinho. "Time to let the world know. My next destination is @ManUtd," Ibrahimovic said on Twitter.
Paul Pogba could spearhead Manchester United's Premier League title challenge if the playmaker can be lured back to Old Trafford, the club's former midfielder Paul Ince has said.
The Colombian forward is heading to Italian champions Juventus on loan.
Leicester City boss Claudio Ranieri is not losing sleep over his team's Premier League title defence and believes the pressure to succeed is more on the new managers of the big-name clubs.
News of all that's transpired on and off the football field
Former Manchester United manager Alex Ferguson believes Pep Guardiola will need time to adapt to Premier League football when he takes charge of Manchester City in July but has tipped the Spaniard to be a success. Guardiola has won numerous trophies in Spain and Germany with Barcelona and Bayern Munich respectively but Ferguson feels the English game, known for its fast-paced and physically demanding nature, will pose a completely different challenge. "Without question Pep has got a fantastic work ethic about him. He has got great coaching ability, there is no doubt about that. Man City have made a real coup in getting him," the 13-time league champion told British media.
Jose Mourinho said on Monday he would step up Manchester United's pursuit of Gareth Bale if the Real Madrid winger was left out of the starting line-up in Tuesday's European Super Cup between the Red Devils and the Champions League holders.
Manchester United climb into sixth place with 3-0 West Ham win
Struggling Premier League champions Chelsea have the quality to climb back up the table under interim manager Guus Hiddink, goalkeeper Thibaut Courtois has said.
FA Cup added another incredible chapter to its proud heritage on Saturday as Chelsea and Manchester City were humbled by supposed inferiors.
Guardiola says City's points record may last years
Arsenal can sustain a Europa League challenge but a top-four finish in the Premier League would be the best way to reach next season's Champions League, manager Arsene Wenger has said.
Defender Filipe Luis has rejoined Atletico Madrid from Chelsea in a reported 16 million euro ($17.66 million) deal, the Spanish club said.
Arsenal missed their chance to go back to the top of the Premier League after being forced to play with 10 men for much of the game against London rivals Chelsea on Sunday.
Chelsea turned again to experienced Dutchman Guus Hiddink to guide them out of a crisis when they named him interim manager on Saturday for the rest of the season following the sacking of Jose Mourinho.
Manchester City withdrew from the battle to secure the services of Arsenal's Chilean forward Alexis Sanchez, leaving Jose Mourinho's Manchester United as the most likely destination for the 29-year-old.
This and more from the happenings in the world of football