Defender Patrice Evra headed United ahead from a Robin van Persie corner on 16 minutes but the league's top scorer Michu netted his 13th goal of the campaign, moving the Spaniard one ahead of Van Persie, to level just before the half-hour.
United, who hit the woodwork twice in the second half through Van Persie and Michael Carrick, hold a four-point advantage over Manchester City heading into a busy holiday programme.
United have 43 points from 18 games, followed by City on 39 and four clubs on 30. Chelsea have the chance to regain third place with victory at home to Aston Villa in the late kickoff (1600). (Writing by Justin Palmer; Editing by Clare Fallon)