Patrice Evra put visiting United ahead in the 16th minute when he headed Robin Van Persie's corner kick past goalkeeper Michel Vorm.
Michu tied the score in the 29th when Evra was caught out by Jonathan De Guzman's run and goalkeeper David De Gea could only parry De Guzman's angled shot, leaving Michu in front to tap the ball in.
Van Persie hit the crossbar in the second half for United (14-3-1), which had won five straight league games. Defending champion Manchester City (11-1-6) is four points back, in second place after beating Reading 1-0 Saturday on Gareth Barry's injury-time goal.
Chelsea (9-3-5), reviving since Rafa Benitez took over as manager last month, moved up to third as seven players scored against American goalkeeper Brad Guzan. The Blues matched their largest league win, 8-0 over Wigan on May 9, 2010.
After Fernando Torres's header in the third minute, David Luiz, Branislav Ivanovic, Frank Lampard, Ramires (twice), Oscar and Eden Hazard also scored.
"We are enjoying playing again and we needed that attitude to get us out of the sticky patch we were in," Lampard said.
Lampard made his 500th Chelsea appearance and scored made his record 130th first-tier goal for the club, surpassing the mark Bobby Tambling set from 1959-70.
It was the largest margin of defeat for Villa (4-8-6) in a league match. Guzan made several good saves and stopped Lucas Piazon's penalty kick in the 89th minute.
At Swansea, tempers flared late when Swans captain Ashley Williams cleared the ball straight into Van Persie's head from close range while the United forward was on the ground.
Van Persie reacted angrily and squared up to Williams with referee Michael Oliver giving yellow cards to both players.
United manager Alex Ferguson called it a "disgraceful act" by Williams.
"The Van Persie situation you can clearly see that he could have been killed," Ferguson said.
He should be banned for a long time because that was the most dangerous thing I've seen on a football field for many years. It was absolutely deliberate. he whistle has gone, the game has stopped and he has done that right in front of the referee. He could have killed the lad."
Williams downplayed the incident.
"I tried to clear the ball; it hit him on the head," he said. "I was trying to clear the ball. He was obviously a bit angry about that. It was a much ado about nothing."
PARIS (AP) — Andre Ayew scored on a header in first-half stoppage time and Marseille beat Saint-Etienne 1-0 at home to head into the winter break tied with leader Paris Saint-Germain and second-place Lyon.
The French title race is the closest among the top five leagues in Europe, with only goal difference giving PSG the edge over Lyon and third-place Marseille after 19 matches.
Marseille has won its past three league games, while Saint-Etienne has failed to win and score a goal in its past six.
At the end of a scrappy first half, right back Rod Fanni burst forward and whipped in a superb cross toward the penalty spot, and Ayew climbed above his marker to send a powerful glancing header past goalkeeper Stephane Ruffier.