JOIN USChelsea held by resilient Hull City
Didier Drogba's free kick shortly before halftime cancelled out Hull's opener scored by Steven Mouyokolo but Chelsea could not force the winner after the break despite late pressure.
Carlo Ancelotti's Chelsea have 55 points from 24 games with champions United on 53. Third-placed Arsenal, who play at Chelsea at the weekend, are on 49 points.
Hull, one of four sides on 21 points near the foot of the table, remain in the relegation zone on goal difference.
Chelsea began well with Frank Lamaprd and Michael Ballack both forcing Hull keeper Boaz Myhill into early action but they lost their way as the first half wore on and fell behind to the kind of set piece that has troubled them all season.
Stephen Hunt swung in a corner and Mouyokolo found himself unmarked to head past Petr Cech from close range.
However, Hull's joy was cut short three minutes before half-time when Drogba curled in a free kick.
Meanwhile, Chelsea will give captain John Terry time off to resolve problems in his personal life if he wants, according to reports in the British media on Wednesday.
Terry could fly to Dubai to visit his wife Toni in 10 days and miss the FA Cup fifth-round tie against Cardiff City.