Samuel Eto'o's hat-trick saw Chelsea to a 3-1 win over Manchester United at Stamford Bridge on Sunday that piled the pressure on the Premier League champions.
Victory left Jose Mourinho's Chelsea within two points of leaders Arsenal but this result meant title-holders United are 14 points adrift of the Gunners with 16 league games of the season remaining.
United's seventh league loss this term also turned the spotlight back on David Moyes, the successor chosen by Alex Ferguson, British football's most successful manager, to replace him at Old Trafford following his retirement at the end of last season.
Eto'o gave Chelsea a 17th minute lead when his shot from just outside the box deflected off Michael Carrick's outstretched boot and past the despairing dive of United goalkeeper David de Gea.
The 32-year-old veteran Cameroon striker made it 2-0 on the stroke of half time when, following Gary Cahill's centre, he smashed the ball home from six yards out.
United, without injured strikers Wayne Rooney and Robin van Persie, found themselves 3-0 behind four minutes after the interval when more lax defending from a set-piece allowed Cahill a free header from a few yards.
His effort was just about blocked by de Gea but, barely a yard away, Eto'o reacted first and made no mistake with the simple chance.
In the process Eto'o become the first Chelsea player to score a hat-trick against United since Seamus O'Connell back in 1954.
Javier Hernandez, on as a substitute for Ashley Young, pulled a goal back 12 minutes from time.
But that was as good as it got for United whose misery was compounded when captain Nemanja Vidic sent off in stoppage time for a rash challenge on Eden Hazard.
Earlier, Emmanuel Adebayor scored twice as Tottenham Hotspur moved level on points with fourth-placed Liverpool after a 3-1 win away to struggling Swansea.
Adebayor's goals, separated by a Chico Flores own-goal, ensured Tottenham remained unbeaten in the league under manager Tim Sherwood, whose record now stands at five wins and a draw since the Englishman replaced sacked predecessor Andre Villas-Boas.
For Swansea, an eighth successive league match without a win left Michael Laudrup's men just three points above the relegation zone.
After Swansea's Wilfried Bony had hit the crossbar with the match still scoreless, Adebayor gave Spurs the lead, against the run of play, in the 35th minute when he headed in an excellent cross from Christian Eriksen.
And the north London side made it 2-0 in the 53rd minute when Flores turned Kyle Walker's cross into his own net with Spurs' Nacer Chadli waiting behind him.
Adebayor put the result beyond doubt 19 minutes from time when, with Swansea's defence opened up again, he turned in Danny Rose's ball across the six-yard box.
Bony scored seven minutes later with a shot from the edge of the box but it was all too late for Swansea.
"Even when they (Swansea) were having a lot of possession I thought we were the most dangerous side and it was just a matter of time before we clicked and found that final ball, and we did that many times in the second half and we could have gone on and won more comfortably," Sherwood told Sky Sports.
Sherwood said that Adebayor's rediscovered hunger and form after he became disillusioned and was marginalised under Villas-Boas was a boost both for the club and the player.
"It's great. It's obviously great for the football club and great for Ade himself, who's flying at the moment and enjoying his football."
