The Saints twice took the lead through striker Graziano Pelle but couldn't hold on as first Erik Lamela and then the Belgian star struck back on the south coast
As Mauricio Pochettino returned to the stadium that he left last summer to join Spurs, the hosts took the lead when the Italian striker capitalised on a defensive nightmare from the north Londoners, with both Ryan Mason and Ben Davies at fault.
Erik Lamela, however, got one back just before the break when his slight touch came off goalkeeper Kelvin Davis on its way through.
A powerful Pelle header restored the Saints' advantage in the second half but, five minutes later, Nacer Chadli outmuscled Maya Yoshida to fire a low shot past Davis, leaving neither side with what would have been a valuable points boost in the race for the Europa League.
|VIEW FROM ST MARY'S
|By Liam Twomey
This was a strange and entertaining match that, in truth, highlighted the reasons why Southampton and Tottenham will fall agonisingly but deservingly short of a top-four place.
Both sides were undone by poor defending and profligate finishing at various points of a game that ebbed and flowed at St Mary's Stadium, though Ronald Koeman can take great heart from the apparent rejuvenation of Graziano Pelle and Morgan Schneiderlin was once again the outstanding player on the pitch.
Mauricio Pochettino, meanwhile, will be immensely grateful to Nacer Chadli for sparing him a defeat in front of a crowd who left him under no illusions as to their feelings for their former manager. Tottenham needed goals from less likely sources - and less likely body parts in the case of Erik Lamela - on a day that saw both Harry Kane and Christian Eriksen fade into the periphery.
There may be four matches still to go but both Southampton and Spurs would be well advised to start planning for a Europa League campaign.
Lloris was left helpless four minutes later, however, as Tottenham gifted the lead to their opponents. Mason slipped and played a pass back towards his own goal after a Southampton counterattack had broken down. Davies was then caught out as he attempted to shield the ball, with the alert Pelle sticking out his left boot and prodding past the keeper.
An unmarked Steven Davis should have done better when side-footing wide from 15 yards in the 39th minute and that miss was punished as an Eric Dier cross took a slight deflection and appeared to strike Lamela on the left arm to wrong-foot Kelvin Davis.
Having missed a presentable opportunity before to the interval, midfielder Davis failed to test Lloris on two further occasions inside the first nine minutes of the second half, dragging a shot wide from the edge of the box before missing the target once more after excellent work from Pelle.
Tottenham came close to taking the lead against the run of play when a Chadli cross deflected off Nathaniel Clyne and narrowly over the crossbar.
Ward-Prowse, who had come in for Dusan Tadic in Southampton's only change pregame, was replaced by Shane Long after 62 minutes as the hosts sought a winner and the substitute made a swift impact, crossing for Pelle to capitalise on poor marking with a firm header into the top-left corner.
Tottenham dug deep to find another response, Chadli holding off Yoshida and directing a low finish across Davis for his 10th Premier League goal of the season following Dier's slide-rule pass into the right channel.
After Spurs left-back Davies was forced off with an apparent shoulder injury, Southampton came closest to a winner - Jose Fonte seeing one header blocked by Federico Fazio and another fly just over - but Pochetino had reason to be content on his return to a club whom he claimed to "still love" prior to kick-off.