City stay clear of United - Van Persie hat-trick floors Chelsea
City overcame a second-half red card for Vincent Kompany to beat Wolverhampton Wanderers 3-1 and defending champions United won 1-0 at Everton, but the most notable result was at Stamford Bridge, where Robin van Persie scored a hat-trick for the visiting Gunners.
André Santos and Theo Walcott got Arsenal's other goals as their club recorded its best win at Chelsea since 1934.
"You could see how happy we are at the end because we fought hard and every one of us showed character," van Persie said. "It's a big, big win for us today."
Victory took Arsenal to 16 points, just three fewer than third-place Chelsea.
Also yesterday, Liverpool won 2-0 at West Bromwich Albion, Blackburn drew 3-3 with Norwich, Aston Villa drew 2-2 at Sunderland, Swansea beat Bolton 3-1 and Fulham won 2-0 at Wigan.
Chelsea notch first goal
Frank Lampard put Chelsea ahead in the 14th minute and van Persie equalised 22 minutes later. John Terry restored the Blues' lead just before half-time, but Santos replied in the 49th and Walcott then put Arsenal ahead.
Juan Mata equalised with 10 minutes remaining with a swerving shot from outside the area, but a poor pass by Florent Malouda combined with a slip from Terry allowed van Persie to round goalkeeper Petr Cech and roll the ball in unchallenged.
The Dutchman then rounded off a swift counter-attack in the final minute to complete his hat-trick and secure Arsen's best win at Chelsea since a 5-2 victory in 1934.
After losing three of their first five Premier League games this season, Arsenal have now won three in a row.
A week after dismantling United 6-1 to take charge of the division, City went ahead early in the second half against a side they beat 5-2 in midweek League Cup action.
Wolves goalkeeper Wayne Hennessey excelled in the first half, but failed to deal with a simple back pass in the 52nd. Sergio Aguero challenged him and the ball spun out to Edin Dzeko, who lifted it into the net for a fifth goal in three games.
Hennessey then parried David Silva's 67th-minute shot from the edge of the box into the path of defender Aleksandar Kolarov, who tucked away an easy finish.
City were cruising, but was reduced to 10 men when Joe Hart spilled a shot from Adlene Guedioura and Kompany was adjudged to have impeded Kevin Doyle as the forward attempted to get to the rebound. Kompany was shown a straight red card and Stephen Hunt scored from a penalty kick.
Wolves pressed for an equaliser, but the home side prevailed when Adam Johnson collected Yaya Toure's pass and fired in.
"I don't know how many chances we had in the first half today, but their goalkeeper saved everything," City manager Roberto Mancini said. "After the Man United win, I don't want us to think that every game will be easy. This does not exist in football."
While City stayed ahead of Manchester United, Wolves are now winless in eight league games.
MAn u beat everton
United moved on from their derby humiliation against City with a hard-fought 1-0 win at Everton, with Javier Hernandez's close-range finish in the 19th enough to earn the defending champions their first victory at Goodison Park since 2007.
"It's an important result to come away from home and win," Ferguson said. "Everton is never an easy game and they put everything they could into the game. In the first half we played some fantastic football and scored a good goal. We have worked hard for this result. It was what we wanted and we battled hard for this.
"The goal was a brilliant goal by Hernandez, he did what he does best."
Charlie Adam scored a penalty and Andy Carroll added a goal just before half-time to give Liverpool a 2-0 win that took the Reds to 18 points and fifth place.
Bradley Johnson and Grant Holt scored in the last nine minutes as Norwich rallied from 3-1 down to draw against Blackburn, who were replaced at the bottom of the standings by Wigan. American forward Clint Dempsey and Moussa Dembele gave Fulham a 2-0 win at Wigan.
Stephane Sessegnon scored with a minute left to save a point for Sunderland, and Danny Graham scored for both sides as his Swansea side beat Bolton 3-1.
Tottenham host Queens Park Rangers today, while Stoke host Newcastle in tomorrow's game.

