Southampton twice came from behind to secure a draw away against the league leaders in a six-goal thriller.
The Saints initially took the lead at Old Trafford through Marian Pahars's 17th-minute opener, but Teddy Sheringham and Dwight Yorke hit back to give Manchester United the half-time advantage.
Matt Le Tissier equalised soon after the break before Yorke responded and put the hosts back in front. But Le Tissier struck again in the 73rd minute to earn a point.
Man Utd remained top of the table but Leeds United and Arsenal both moved within two points of them. Southampton stayed 13th.
Promoted Sunderland recorded their first Premier League victory of the season at the seventh attempt and moved off the foot of the table.
Tommy Miller gave the visitors the perfect start at the Riverside Stadium, scoring in just the second minute, and Julio Arca doubled the lead with a free-kick on the hour-mark.
Sunderland climbed above Everton into 19th place with four points, while Middlesbrough slipped to 11th with eight points.