Southampton - Southampton's Champions League aspirations suffered a blow as Jonjo Shelvey's long-range goal earned Swansea City a smash-and-grab 1-0 win in the Premier League on Sunday.
In a weekend when their leading Premier League rivals proved they are slowly gathering momentum, the Saints lost precious ground.
While they remain fourth, a point below third-place Manchester United, they lead Arsenal only on goal difference, and Tottenham Hotspur and Liverpool are also closing in.
Shelvey's late strike was out of context with the rest of the match, but that was of no concern to Swansea, who climbed to ninth in the table.
A miserable afternoon for Southampton was rounded off by a red card shown to Ryan Bertrand for a reckless challenge.
Prior to the match, it had appeared to be a good time for Southampton to be playing Swansea. Without a win since Boxing Day and on the back of an FA Cup exit at Blackburn Rovers' hands, Swansea seemed at a crossroads.
The Welsh side have been struggling for form and with key man Gylfi Sigurdsson suspended, following on from the sale of Wilfried Bony to Manchester City, it promised to be a testing experience for Swansea manager Garry Monk on his return to his old club.
Southampton started brightly. Nathaniel Clyne's cross found its way to James Ward-Prowse, who saw his low shot kept out by Lukas Fabianski's outstretched boot.
Swansea rarely ventured forward and were content to sit back and soak up the early pressure.
They did threaten when Bafetimbi Gomis drove just wide after collecting Shelvey's clever pass.
And while Southampton dominated possession, whenever a player from the home side threatened to break free, he was quickly surrounded by white shirts.
That was the case on the half-hour mark when Dusan Tadic could not turn Eljero Elia's cross home under pressure from Neil Taylor.
The start of the second half continued the theme of the first period. Swansea continued to sit back, with Gomis their only man in front of the ball on most occasions.
Southampton have the league's tightest defence and are the Premier League's highest scorers at home, but the game seemed destined for a stalemate until Shelvey came to life.
On the hour, the former Liverpool midfielder made room for himself and his driving run ended with a 25-yard shot that rebounded off the foot of the left-hand post.
It could have provided the spur that Southampton needed as Ward-Prowse tested Fabianski twice in quick succession, but it was Swansea who went ahead in the 83rd minute.
Picking the ball up 30 yards from goal, Shelvey neatly skirted an opponent and then rifled a right-foot shot past Fraser Forster to silence St Mary's.
Sadio Mane saw two efforts cleared off the line by Ashley Williams, but Southampton had long run out of ideas.
Bertrand's red card just moments before the final whistle for a wild challenge on Modou Barrow summed up an afternoon to forget for Ronald Koeman's hosts.
The left-back had to be dragged down the tunnel after a spat with Monk that could land him in hot water.