Manchester City's expensively assembled squad showed Sunday that it may have the character as well as the talent necessary to win the Premier League, beating Arsenal 1-0 to stay top of the standings.
Manchester United's 2-0 win at Queens Park Rangers in the day's early match meant City knew it had to avoid defeat or lose the top spot it had held since mid-October.
City went one better, beating Arsenal 1-0 to stay two points ahead of its local rival.
David Silva capped a period of sustained pressure by City with the only goal in the 53rd minute and goalkeeper Joe Hart made a string of saves to keep Arsenal out.
"We watched Man United, so we knew we had a job to do this afternoon," Hart said.
Wayne Rooney and Michael Carrick scored for United, while Tottenham beat Sunderland 1-0 to take third place. Liverpool won 2-0 at Aston Villa in the day's other match.
As well as having to respond to United's convincing win over a team that has beaten Chelsea and unsettled City this season, City had to get over the loss of its unbeaten Premier League record to Chelsea on Monday.
Both teams attacked from the start in an open game, but City gained the upper hand and Mario Balotelli burst into space and drew a save from Wojciech Szczesny with a shot low to the goalkeeper's left. The ball rebounded into the six-yard box and Silva poked it in from close range.
Robin van Persie, the Premier League's leading scorer, had an equalizer ruled out because of a narrow offside decision and Hart made several saves. The best stop came when he pushed a late shot over the bar from Thomas Vermaelen, who also shot narrowly wide from long range.
"Both teams played in a positive spirit and went for it with a positive philosophy," Arsenal manager Arsene Wenger said.
Rooney scored his 15th goal of the season — and 12th in the Premier League — after just 52 seconds. The England striker headed the ball out to Antonio Valencia on the right and continued his run into the box to meet Valencia's cross with a stooping header into the net.
Carrick then intercepted a pass just inside the United half and advanced to the edge of the area to hit a low shot past goalkeeper Radek Cerny for his first goal in almost two years.
United could easily have scored more, with Phil Jones hitting the post and a couple of moves breaking down on the final pass.
The defending champions have 39 points from 16 matches — five more than at the same stage last season when it went on to win a record 19th English league title — but City has 41 and has scored an impressive 50 goals.
"We could have scored a lot of goals today," Manchester United manager Alex Ferguson said. "Queens Park Rangers in their home games have been a real problem to a lot of teams, but we kept them quiet for most of the game."
Arsenal's first loss in nine league matches left it in fifth place with 29 points, ahead of Liverpool only on goals scored.
Liverpool scored from corner kicks twice in the first 15 minutes at Aston Villa. Craig Bellamy poked in from close range after the ball hit goalkeeper Brad Guzan and then took a corner on the left, sending the ball onto Martin Skrtel's head for the unmarked defender to score.
"We passed the ball and moved it and hit the bar twice: I think it was well deserved three points for us," said Liverpool's Kenny Dalglish after his first league win as a coach at Villa Park. "The first goal was a little bit fortunate but the second one was a good flick-on from Martin."
Tottenham is again the closest rival to the two Manchester clubs after a 1-0 win over Sunderland took it above Chelsea into third place.
Spurs dropped to fourth last week when its 11-match unbeaten run came to an end at Stoke but swiftly recovered to take advantage of the Blues' 1-1 draw with Wigan on Saturday.
On the field as a first-half substitute for injured winger Aaron Lennon, Roman Pavlyuchenko scored the winning goal in the 61st. Scott Parker slipped the ball upfield to Rafael van der Vaart for a clever reverse pass to Pavlyuchenko, who scored past the diving goalkeeper with a low shot to the far post from the edge of the area.
Pavlyuchenko's first league goal of the season pushed Tottenham two points ahead of Chelsea with a game in hand.
Southampton leads West Ham by one point at the top of the second-tier League Championship after a 1-1 draw with south coast rival Portsmouth.