MANCHESTER UNITED blew the chance to third after Michael Obafem equalised for Southampton in the 95th-minute.
Ole Gunnar Solskjaer’s side came into the clash on a fine run of 17 matches unbeaten and five straight wins.
Marcus Rashford levelled the score on 20 minutes
But they were stunned at the death as the sub popped up to prod home a corner to keep United fifth.
Old Trafford went into shock early doors when a Paul Pogba mistake led to Stuart Armstrong firing the visitors ahead.
However, the in-form Red Devils quickly bounced back through Marcus Rashford and Anthony Martial.
The England striker struck first on 20 minutes before the Frenchman turned the scoreline on its head just three minutes later.
And they looked on course to claim the points until the dramatic finish.