Manchester United moved to within a point of Arsenal at the top of the Premier League on Saturday after the Gunners drew 1-1 with visiting Aston Villa.
Arsenal almost lost at Emirates Stadium after defender Philippe Senderos scored a 27th-minute own-goal, but Nicklas Bendtner equalized in the last minute to salvage a draw.
Even so, defending champion United, which had trailed by five points eight days ago, closed the gap with a 3-0 win at Fulham.
Chelsea recovered from last weekend's League Cup final defeat to Tottenham with a 4-0 win at London rival West Ham, while Spurs rested several players after winning their first trophy for nine years and lost 4-1 at Birmingham.
Arsenal now has 65 points from 28 matches, but United's goal difference is seven better than the leaders' and Chelsea is six points back having played one game fewer.
"If it comes down to goal difference, it could make a difference," United manager Alex Ferguson said. "The way it's been going in the last few weeks, it's been a bit of a seesaw. But we have to look over our shoulder because Chelsea's score today was emphatic."
Fourth-place Everton hosts Portsmouth on Sunday, while sixth-place Liverpool is at Bolton. But at the other end of the standings, Newcastle slipped to within three points of the relegation zone after a 1-0 loss to visiting Blackburn.
Arsenal was desperate for victory after last week's 2-2 draw at Birmingham, in which it lost striker Eduardo da Silva to a career-threatening leg injury. It dominated the early exchanges as striker Theo Walcott had a shot saved by Villa goalkeeper Scott Carson and almost created another opportunity.
Senderos shot wide from inside the area after Carson had dropped the ball from a corner, but, four minutes later, scored past his own goalkeeper when he tried to intercept a cross by Gabriel Agbonlahor.
Villa lost Nigel Reo-Coker and Curtis Davies to injury, but almost went 2-0 ahead before halftime when home keeper Manuel Almunia had to push a 20-meter shot by Shaun Maloney onto the crossbar.
Arsenal pushed for a late equalizer and Bendtner managed it with a close-range shot.
"In the first half, you could see it was a hangover from last week," Arsenal manager Arsene Wenger said. "We were dominated physically and technically ... but this shows the team never lies down."
Fulham goalkeeper Antti Niemi had already saved from Nani and Carlos Tevez before Tevez won a free kick just outside the area in the 15th. Owen Hargreaves curled the ball over the defensive wall and wide of Niemi to make it 1-0.
Park Ji-sung scored a minute before halftime with a header and Simon Davies completed the scoring midway through the second half, with an own-goal.
"It was a professional performance," Ferguson said. "It was windy and in these conditions you have to have good concentration.
"I don't think Fulham were a big threat to us inside the penalty box, but outside they played some good stuff."
Chelsea responded to reports of unrest in its expensively assembled squad with a convincing win at Upton Park, with the recalled Joe Cole and Michael Ballack both scoring as the Blues went 3-0 up in the first 22 minutes.
Former West Ham midfielder Frank Lampard put Chelsea ahead from a 17th-minute penalty kick after Anton Ferdinand had fouled Salomon Kalou and Cole made it 2-0 in the 20th with a low shot.
Ballack, who, like Cole, was dropped for the League Cup final, put Chelsea further ahead before Lampard was sent off in the 34th for what looked like an innocuous push of Luis Boa Morte in the face.
Still, Ashley Cole made it 4-0 for Chelsea in the 64th.
Tottenham no longer has to worry about its league position after qualifying for next season's European competition by winning the League Cup, so it rested players including Robbie Keane, Ledley King and Jonathan Woodgate to prepare for Thursday's UEFA Cup match against PSV Eindhoven.
But Birmingham punished Tottenham for taking the match lightly and Mikael Forrsell scored a hat trick for the Blues, who stay a point clear of the relegation zone.
Reading remained in 18th place with 25 points even though it ended an eight-match losing streak with a 1-0 win at Middlesbrough. But Newcastle is in serious danger of returning to the second tier after 15 years in the Premier League.
Newcastle dominated Blackburn with Michael Owen and Alan Smith missing chances, but Matt Derbyshire scored in injury time to leave the Magpies on 28 points and winless since Kevin Keegan returned as manager in January.
Derby stayed last with 10 points after a 0-0 draw with Sunderland, and Fulham is 19th with 19.
Wigan drew 0-0 at Manchester City in Saturday's other match.
Bristol City moved top of the second-tier League Championship after a 2-1 win over Hull, while idle Stoke dropped to second. Watford was in third place after a 2-2 draw at Burnley, and West Bromwich Albion is fourth after beating Plymouth 3-0.