Samuel Eto'o scored a hat-trick as Chelsea beat Manchester United 3-1 to reduce the gap to Premier League leaders Arsenal to two points.
The Cameroon international struck twice in the first half and was on target again just after the break at Stamford Bridge to take his tally to eight goals for the season as third-placed Chelsea stretched their winning run to six games in all competitions.
Javier Hernandez pulled a goal back for United after coming off the bench, but It was another miserable afternoon for boss David Moyes, who will also now be without his captain Nemanja Vidic for a spell after he was sent off in injury time for a wild challenge on Eden Hazard.
Defeat saw Moyes' side beaten for the first time away from home in the league for almost four months, as their chances of retaining their title were made even more remote.
The champions are 14 points behind Arsenal and now face a battle to even qualify for the UEFA Champions League, sitting six points adrift of fourth-placed Liverpool.
Jose Mourinho has no such problems, as he celebrated his 100th Premier League win in only 142 games - requiring less matches than any other manager to achieve the landmark.
Chelsea defender Branislav Ivanovic returned from injury ahead of schedule at the expense of Ashley Cole, while Eto'o was preferred to Fernando Torres. New signing Nemanja Matic started on the bench alongside fit-again midfielder Frank Lampard.
Ashley Young and Phil Jones were back in the United starting line-up as Shinji Kagawa and Chris Smalling dropped to the bench.
United made an encouraging start, but they found themselves behind after 16 minutes when Eto'o conjured up a goal out of nothing.
There appeared to be no danger when the striker picked up a loose ball, but he cut in from the right and jinked past Jones before unleashing a shot from the edge of the penalty area that deflected off Michael Carrick and looped into the far corner of the net.
United responded well to going behind and the lively Adnan Januzaj created a great chance for Danny Welbeck when he picked out the striker in the area, but the England international's tame finish was saved by Petr Cech.
That miss proved to be costly too, as Gary Cahill picked out Eto'o a minute before half-time and the Cameroon international finished from six yards out.
Eto'o then made United pay for some poor defending just three minutes into the second half to complete his treble.
He was first to react when Cahill's header was well saved by De Gea - the alert striker on hand to tuck home the rebound.
Welbeck's frustrating afternoon continued when he headed wide from six yards out, but substitute Hernandez did pull a goal back when he turned in Jones' shot from inside the six yard box 12 minutes from time.
It was too little, too late for Moyes' side though, and Matic came on to make his second debut for Chelsea five minutes from time after rejoining from Benfica as they saw out the victory with ease.
United’s misery was complete when Vidic was then shown a straight red card for a cynical challenge on Hazard, while Rafael was lucky to escape with just a yellow after lunging at Cahill.
|29||S. Eto'o||17' 45' 49'|
|Coach: José Mourinho|
for Oscar 68'
for S. Eto'o 79'
for Willian 86'
|Emery: PSG cannot rely solely on Cavani goals|
|Mourinho can match Guardiola, insists Ferguson|
|Ferguson hails Klopp: Liverpool are strong title contenders now|
|Bayern optimistic over Lewandowski renewal|
|Zubizarreta appointment confirmed by Marseille|
|Clichy: Things will click into place for Manchester City|
|Chiellini: Juventus wanted to send a message|
|Gabigol´s time will come - De Boer|
|Ronaldo: Messi and I are not friends - but we respect each other|
|Earthquake halts play in Serie A game between Pescara and Atalanta|
|Mourinho charged over Taylor comments|
|Ronaldo: I need my haters|
|Badstuber hopeful injury woes behind him|
|Kroos did not want to be rested, insists Zidane|
|Rojo was phenomenal - Mourinho|
|Seven arrests made after West Ham - Chelsea fan clashes|
|Florenzi injury blow for Roma|
|MLS Review: Galaxy, Toronto into semis|
|Beister: Victory move surprised people|
|Bilic: Cup run will help in Premier League|
|Pjaca out for up to three weeks|
|Trophies still the focus for Guardiola|
|Mignolet wants ´fair´ Karius battle|
|Ancelotti impressed by motivated Bayern|
|West Ham ´unreservedly condemn´ crowd trouble|
|Allegri praises strike duo after win over Sampdoria|
|De Boer praises two-goal Icardi after vital win|
|Chelsea were ´unlucky´ with missed chances, insists Conte|
|Mourinho: I´ve never had fans like these|
|Nacho´s goal better than my Champions League final volley - Zidane|
|Borussia Dortmund 1 Union Berlin 1 (aet, 3-0 pens): Weidenfeller shootout heroics seal progress|
|Bilic: Crowd trouble distracts from great West Ham win|
|Kompany told me he couldn´t play anymore - Guardiola|
|Liverpool and Manchester United handed home quarter-finals|
|Inter 2 Torino 1: Icardi double alleviates pressure on De Boer|
|Manchester United 1 Manchester City 0: Mata extends Guardiola´s winless run|
|West Ham 2 Chelsea 1: Crowd trouble tarnishes Hammers´ route to quarter-finals|
|Cultural Leonesa 1 Real Madrid 7: Morata and Asensio star in BBC´s absence|
|Bayern Munich 3 Augsburg 1: Green´s first goal sends holders through|
|Juventus 4 Sampdoria 1: Rapid start sets champions on their way|
|Crafty Suarez is world´s best striker - Godin|
|Mancini: Balotelli has wasted years but can bounce back|
|Rami rejected ´risky´ PSG move|
|Neymar would have cost PSG €430m, claims father|
|Sacchi warns Bayern players over Ancelotti temper|
|Valencia ´pleased´ with RFEF bottle ruling|
|Mourinho apologises to Utd fans for Chelsea thrashing|
|Barcelona lash out at ´totally reprehensible´ RFEF comments|
|Jacob leaves Marseille amid rumours of Zubizarreta appointment|
|Lavezzi added to Argentina squad as Dybala drops out|
|Del Bosque: Mourinho had a point on Conte|
|N´Zonzi in talks over Sevilla extension|
|Allardyce successor ´will not be a mercenary´ - Glenn|
|Aubameyang like a rocket, Lewandowski perfect - Riedle|
|RFEF fines Valencia, warns Barca over bottle incident|
|Wenger tells Iwobi to improve his finishing|
|Barcelona without Mathieu for three weeks|
|Kimmich draws inspiration from Xavi|
|Vazquez signs new Madrid deal|
|Higuain the best striker in the world - Nedved|
|Wolfsburg regret De Bruyne, Perisic sales|
|Parejo slams Neymar for ´inciting´ Valencia fans|
|Gundogan predicts ´very lively´ Manchester derby|
|Luis Enrique satisfied with Supercopa workout|
|Messi could join Newell´s after World Cup - Maxi Rodriguez|
|Ibrahimovic wants United to be the boss of City|
|Schmidt on the bus as Lotte book ticket for next round|
|Pogba still adapting to Premier League, says Mourinho|
|Southgate hails influence of demoted Rooney|
|Lille ready to heap more pressure on PSG as Corchia dreams big|
|I´m among top 20 LaLiga coaches, jokes Luis Enrique|
|Brattan earns Socceroos call-up|
|Pochettino pleased with Janssen|
|Klopp never questioned Sturridge quality|
|Barcelona downed by Espanyol in Supercopa|
|Heavy Milan defeat ´just a bump in the road´ - Montella|
|Pochettino wanted Liverpool debutant sent off|
|Klopp happy to entertain as Liverpool youngsters earn their spurs|
|Leverkusen dumped out by 10-man minnows|
|Wenger praises Oxlade-Chamberlain work ethic|
|Wenger praises Oxlade-Chamberlain work ethic|
|Tuchel unaffected by Real Madrid rumours|
|I would like to pick Toure, believe me - Guardiola|
|Genoa 3 AC Milan 0: Unbeaten run comes crashing to an end as Paletta sees red|
|Liverpool 2 Tottenham 1: Sturridge at the double to book quarter-final spot|
|Arsenal 2 Reading 0: Oxlade-Chamberlain brace secures safe passage|
|Football world mourns Carlos Alberto|
|81 per cent win ratio and more goals than Bayern Munich - Two years of Messi, Suarez and Neymar|
|Ridgewell reportedly arrested for drink driving|
|Verratti not leaving PSG - agent|
|Costa competition benefitting Batshuayi, says Conte|
|Pele hails ´friend and brother´ Carlos Alberto|
|Bailly confirms two-month lay-off|
|How Carlos Alberto established his legacy as one of the greats|
|Allegri hints at Marchisio return|
|Lewandowski has not renewed with Bayern - agent|
|Carlos Alberto: Capita´s World Cup triumph in numbers|
|Hull´s Snodgrass out for a month|
|Keita reveals Arsenal, Manchester City, Liverpool snub|
|Mikel not giving up on Chelsea career|
|Former Brazil captain Carlos Alberto dies|
|Guardiola wants to help ´special player´ Aguero|
|Roma welcome back Strootman, Rudiger for Sassuolo clash|
|Wolves confirm Zenga dismissal|
|Bruce lauds Rooney as a world ´great´|
|Raiola made €27m on Pogba move, reveals Juventus director|
|Dortmund injury woes worsen with Aubameyang|
|De Bruyne out of Manchester derby|
|Conte: I always show respect to opponents|
|FIFA fines RFEF over Madrid, Atletico breaches|
|Pedro backs Conte amid Mourinho spat|
|Big clubs would fight for Edwards if he was Brazilian - Pochettino|
|They boo Ronaldo, they booed me as well - Zidane|
|De Boer fed up of sacking talk|
|Neuer: Bayern have no room for error|
|Bilic praises Conte´s ´aggressive´ demeanour|
|Di Maria will bounce back - Motta|
|EFL opens investigation into Watford over ´forged´ bank letter|
|Hummels admits RB Leipzig a serious threat for Bayern|
|Pedro reveals Barcelona talks|
|De Bruyne: I have no problem with Mourinho|
|Casillas: I have not retired from Spain duty|
|Raul backs under-fire Ronaldo for Ballon d´Or glory|
|Mourinho and United must lower expectations - Xavi|
|Hands off! Milan CEO insists Donnarumma will stay|
|Glory coach Lowe accepts ban|
|Scolari extends contract with Guangzhou Evergrande|
|Guardiola eliminated City doubts - De Bruyne|
|Klopp lauds Ings for ´perfect´ response|
|Wenger: Perez needs to take chance|
|Boys to men: Mourinho challenges United players|
|Kompany committed to bargain with City medics|
|´Insipid´ Hazard overlooked for Ballon d´Or|