They moved above United, albeit only on goal difference, when Tranmere keeper Gavn Ward fumbled the ball into his own net when challenged by Chris Hall.
Nottingham Forest's promotion push was hit by a 2-2 draw at Bradford, with Billy Paynter hitting a late equaliser for the Bantams.
Yeovil still look on course for the play-offs despite a surprise home loss to Millwall, with Ben May scoring the only goal of the game for the London side.
Fellow play-off chasers Swansea City also dropped points, as they crashed 2-1 at Cheltenham Town.
Brentford hauled themselves off the foot of the table with a surprise 3-1 success at Blackpool.
Doncaster crashed to a 2-1 defeat at home to Carlisle, with Karl Hawley scoring an impressive second-half winner for the Cumbrians.
Huddersfield eased to a 3-1 home win over Gillingham at the Galpharm Stadium to keep alive their flagging play-off hopes.
Crewe increased the pressure on Northampton with a 2-1 win at Sixfields, leaving the Cobblers 19th in the table.
Leyton Orient boosted their hopes of surviving the drop with a 2-1 victory over Port Vale at Brisbane Road.
Bournemouth finally grabbed their first away win of the season with a 1-0 success at Chesterfield, while Brighton and Rotherham played out a goalless draw at the Withdean Stadium.