Erik Lamela scored just his second Premier League goal of the season as Tottenham Hotspur pegged back Southampton to go into half time level at St Mary's.
There were few chances in the opening minutes, in which former manager Mauricio Pochettino was taunted by the home fans on his first return to the club.
The Saints slowly took control of proceedings as Ryan Bertrand's cross caused havoc in the Spurs box and Morgan Schneiderlin forced Hugo Lloris into a smart reflex save.
They took the lead on 29 minutes thanks in part to a pair of Tottenham mistakes. Ryan Mason slipped on the edge of his own box and Ben Davies failed to shield the midfielder's rushed back-pass, allowing Graziano Pelle to prod beyond the rooted Lloris.
Steven Davis squandered a chance to double Southampton's lead when he sliced wide when attempting to side-foot Bertrand's cutback, and Spurs soon went up the other end to punish his wasteful finishing.
The visitors needed a slice of luck in scoring their 43rd-minute equaliser, though. Eric Dier's inviting cross into the box struck an unaware Lamela on the body and squirmed past Kelvin Davis at the near post.
