A Samuel Eto'o hat-trick lifted Chelsea to a 3-1 win over Manchester United on Sunday which all but ended the champions' slim hopes of defending their Premier League title.
Tottenham Hotspur secured a fifth successive away league victory and moved up to fifth place after Emmanuel Adebayor scored twice in a 3-1 win at Swansea City.
Two first-half goals and one soon after the restart by Eto'o took Chelsea up to third place with 49 points, two behind leaders Arsenal, and United remained in seventh place, 14 off the summit.
United defender Nemanja Vidic was sent off in stoppage time to complete a miserable day for David Moyes's team.
"I think it is a big win and deserved, yes," Chelsea manager Jose Mourinho told Sky Sport.
"The way I was analysing the game it was hard for them to be losing 2-0 at halftime. They started better than us, they had a good initiative.
"The second half was different. For 25-30 minutes we had very good control until we dropped back and they reacted with pride.
"I think this game was a bit of a contradiction to other games. Normally we produce and produce and then it is hard for us to score, this time with the first shot we scored. The second goal was the killer in the box I know from many years ago and it looks like Samuel Eto'o is coming back."
United, and young attacker Adnan Januzaj in particular, started brightly but were undone by two poor pieces of defending that allowed Cameroonian Eto'o to score his first goals against United since the 2009 Champions League final when he was playing for Barcelona.
After United's Ashley Young had stung the palms of Petr Cech, Eto'o opened the scoring after 17 minutes when allowed to shoot by Phil Jones, his deflected shot ballooning off the boot of Michael Carrick into the net.
Eden Hazard and Willian showed glimpses of attacking threat but it was United who should have scored next after Januzaj picked out Danny Welbeck in the box, but the England international failed to get a clean shot away under pressure from Cesar Azpilicueta.
Oscar tried his luck with a speculative overhead effort before Eto'o doubled his side's advantage just before the break.
United failed to clear a corner and defender Gary Cahill picked out Eto'o unmarked in the box.
His shot was close to David de Gea but had too much power for the young Spaniard, and he completed his treble from close range when following up Cahill's header to secure a fifth successive league victory for Jose Mourinho's side.
Substitute Javier Hernandez pulled one goal back for United with 12 minutes remaining, but Chelsea were placed under little pressure during a meek second-half performance, and United's misery was compounded when Vidic was given a straight red for a rough tackle on Hazard.
"We did not deserve to be 2-0 down at halftime," Moyes said.
"We had a little bit of bad luck with the first one but we can't blame anyone else but ourselves for the other two. We did not defend well enough and did not get a chance like Chelsea got to score, so we can only blame ourselves for that."
Adebayor opened the scoring for Spurs after 35 minutes with a near-post header from Christian Eriksen's cross, and after Chico Flores turned a Kyle Walker cross into his own net early in the second half, the Togo striker made it 3-0 with 19 minutes left having been set up by Danny Rose.
Wilfried Bony capped a tireless effort by pulling one goal back for the hosts who now sit three points above the relegation zone.
Spurs are level on 43 points with Liverpool, although Everton could overtake them both with victory over West Bromwich Albion on Monday.
Defeat prolonged a dire run for Michael Laudrup's Swansea who have failed to win in eight league matches dating back to early December.
Adebayor has five league goals since being recalled to the team by manager Tim Sherwood, who replaced Andre Villas-Boas last month.
"I can't take the credit for Emmanuel Adebayor, he has to take the credit," Sherwood said.
"I have just given him the stage to go and perform.
"It's not as if he was never a good player. He was always a fantastic player. Everywhere he has been he has scored goals. He is enjoying his football at the moment and we are all reaping the rewards from it."