Manchester United's top-four hopes were hit as they conceded a half-time lead again and were held to a 1-1 draw by Southampton thanks to Che Adams' 48th-minute goal.
Cristiano Ronaldo almost put Man Utd ahead at Old Trafford early on, but his effort was cleared off the line by Romain Perraud.
United took the lead on 21 minutes, when Bruno Fernandes played a defence-splitting through-ball to Marcus Rashford, who crossed for Jadon Sancho to score his first Premier League goal at Old Trafford.
As with their 1-1 draw at Burnley on Tuesday, United conceded an equaliser shortly after half-time.
Adams, who scored the late winner at Tottenham Hotspur in midweek, latched on to a pass from Mohamed Elyounoussi before firing in via the far post.
Both sides pressed for a winner. Stuart Armstrong blazed over for Saints while Fraser Forster twice superbly denied Harry Maguire from close range.
United rise to fifth on 40 points, behind West Ham United on goal difference but a point above Arsenal having played two matches more.
Southampton are 10th on 29 points.
See: Man Utd report | Southampton report
Next fixtures
Man Utd: 15 Feb v Brighton (H)
Southampton: 19 Feb v Everton (H)
Match officials
Referee: Stuart Attwell. Assistants: Adam Nunn, Nick Hopton. Fourth official: David Coote. VAR: Jarred Gillett. Assistant VAR: Neil Davies.
WHO'S GOING TO BE YOUR
MAN OF THE MATCH?
Vote at Full-time