Chelsea recovered from going behind after 13 seconds to beat Southampton 3-1 at home with John Terry scoring on his 400th league appearance for the club and free-scoring Man City climbed to third after spanking Swansea City 3-0.
City, for whom Samir Nasri netted twice, have now scored 16 goals in their last three home matches.
Liverpool began the day in second place but faltered, losing 3-1 at Hull City.
With a third of the season gone Arsenal lead the standings on 31 points, four more than Chelsea and six ahead of City with Liverpool in fourth, a further point behind.
United are eighth, nine points adrift.
(Reporting by Martyn Herman and Toby Davis, Editing by Ed Osmond)
