Tottenham failed to bounce back from their Barclays Premier League title disappointment as a Steven Davis double sealed a surprise 2-1 victory for Southampton.
Mauricio Pochettino's side needed only a point to guarantee at least third place and looked on course for victory when Son Heung-min gave them early lead but Davis scored twice to ensure Spurs' final home game of the season ended in defeat.
It means Tottenham are now winless in three matches while Southampton move up to sixth and within touching distance of Europa League qualification.
If there were any lingering regrets from last week's surrendering of the title to Leicester it was not immediately obvious as White Hart Lane, bathed in sunshine, enjoyed a jubilant atmosphere, the fans seemingly happy to celebrate the team's remarkable progress this season.
Daniel Levy's gushing chairman's message in the match-day programme was no less appreciative, telling the fans this campaign had seen Spurs "remind us all why we love this game and why we love our club".
There is good reason for the plaudits but two points now from three games threatens to end Tottenham's season on a sour note, particularly if they cede second place to either Manchester City or Arsenal, who have endured a miserable 12 months by their own high standards.
The Gunners, who Spurs have not finished above since 1995, are now breathing down the necks of their north London neighbours, sitting three points behind with a game in hand, which comes against City later on Sunday.
Southampton, in contrast, are sprinting to the finish line, having now equalled their Premier League record points tally of 60 and lost only one of their last nine.
Ronald Koeman's work continues to overshadow the blow of Pochettino's departure two years ago and their priority this summer must surely be to tie their manager down long term.
Christian Eriksen and Dusan Tadic both went close in the opening 15 minutes but Spurs had started brighter and in the 16th minute took the lead when an offside Harry Kane let Erik Lamela's ball run through and as Southampton stopped, Son came alive, nicking the ball round Fraser Forster and slotting home his second in as many games.
The goal was Tottenham's 68th this season, their highest ever tally in the Premier League era, but if the hosts were hoping for end-of-season party in the sun they would soon be disappointed.
Kyle Walker went down after taking an arm to the face and as referee Jon Moss let play continue, Saints pounced, Tadic's cut-back allowing Davis to steer an equaliser under Hugo Lloris, who should have done better from close range.
Tottenham failed to respond when conceding against West Brom and Chelsea last week and it was not until the end of the half they looked like pulling ahead again, when Kane wrestled possession back on the touchline before seeing his angled finish denied by Forster.
The pattern remained set for the start of the second period too, with Spurs enjoying plenty of possession but struggling to break down their opponents, who in turn looked dangerous on the counter-attack.
The danger materialised in the 72nd minute as Davis played a neat one-two with Tadic before curling the ball past Lloris and inside the far post.
Tottenham huffed and puffed in the latter stages but rarely threatened an equaliser, their best chance coming in injury time when a loose ball spilled out to Nacer Chadli but his finish was saved.
TWEET OF THE MATCH
"Pretty impressive from @RonaldKoeman only 2 seasons here and have beaten every team in premier league" - former Southampton midfielder Matt Le Tissier ?@mattletiss
PLAYER RATINGS
Tottenham
Hugo Lloris: 4 (out of 10)
Kyle Walker: 5
Toby Alderweireld: 6
Jan Vertonghen: 6
Danny Rose: 6
Eric Dier: 7
Ryan Mason: 4
Erik Lamela: 6
Christian Eriksen: 7
Son Heung-min: 6
Harry Kane: 6
Subs
Clinton Njie (on for Son, 65): 5
Nacer Chadli (on for Mason, 77): 5
Southampton
Fraser Forster: 7
Cuco Martina: 6
Jose Fonte: 6
Virgil van Dijk: 7
Ryan Bertrand: 7
Victor Wanyama: 7
Jordy Clasie: 6
Sadio Mane: 7
Steven Davis: 8
Dusan Tadic: 8
Shane Long: 7
Subs
Oriol Romeu (on for Clasie, 58): 6
Graziano Pelle (on for Mane, 65): 6
James Ward-Prowse (on for Tadic, 83): 5
STAR PLAYER
Steven Davis: The Saints midfielder had not scored for his club since November but it was the 31-year-old's double that changed the game, his second a cool finish bent into the far corner.
MOMENT OF THE MATCH
The equaliser: Tottenham dominated the opening stages and looked comfortable after Son broke the deadlock but Davis' equaliser after 31 minutes transformed the contest and Spurs were never the same thereafter.
VIEW FROM THE BENCH
Mauricio Pochettino has spoken a lot about his side's resilience and maturity this season but Tottenham have now dropped 20 points from winning positions this season. The Argentinian must find a way to instil his side with more composure when in front. Ronald Koeman, meanwhile, will be delighted to see Southampton follow up last week's win against Manchester City. His team were organised and effective on the counter-attack. European football beckons.
MOAN OF THE MATCH
Hugo Lloris has been one of the stars of Tottenham's season, proving himself as one of the top goalkeepers in the division. But the Frenchman was off-colour here, letting Davis' first-half finish squirm under his body and then seemingly slow to get down to the midfielder's winner.
WHO'S UP NEXT
Newcastle v Tottenham (Premier League, Sunday 15 May)
Southampton v Crystal Palace (Premier League, Sunday 15 May)
Source: PA
