Riyad Mahrez scored twice in the opening 20 minutes to condemn Southampton to a 2-0 defeat against Leicester City at the King Power Stadium.
The loss extends Saints’ run without a win on the road to six games, but Tottenham Hotspur’s defeat to Stoke City means there is still hope in the race for an automatic Europa League place.
Mahrez’s two goals came after the hosts had made a blistering start, with Saints unable to recover at a vibrant King Power Stadium.
Ronald Koeman handed Paulo Gazzaniga a chance in goal, with Kelvin Davis dropping to the bench, in one of four changes to the side from the defeat to Sunderland last weekend.
Harrison Reed, Eljero Elia and Steven Davis were the three outfield players to come in, with James Ward-Prowse missing out through suspension and Shane Long and Maya Yoshida dropping to the bench.
The hosts, with five wins in their last six games, unsurprisingly began brightly and were ahead inside eight minutes.
Mahrez picked up a loose ball midway inside Southampton’s half and after seeing off challenges from Davis and Reed, fired a low ball past Gazzaniga from just outside the box.
It got worse for Saints just 13 minutes later as the hosts took full advantage of a poor clearance to double their lead. Jamie Vardy’s ball across the box found an unmarked Mahrez, who finished calmly to make it 2-0.
At the other end, the first real chance the visitors came and went five minutes later. Davis headed the ball back across goal after Nathaniel Clyne’s cross hadn’t been cleared properly, but Sadio Mané headed over.
Mahrez was causing problems going forward for the hosts and almost added an assist to his two goals. The Algerian international played in Vardy, but Gazzaniga made a smart low save to keep the striker at bay.
In what proved to be the last action of the first half, Toby Alderweireld had a well-struck free-kick palmed away by Kasper Schmeichel, as Saints failed to make the most of 71 per cent possession in the opening 45 minutes.
Saints looked to make a more positive start to the second half but were unable to create any real chances of note. Elia’s shot in anger from distance drifted wide of the target as the Foxes kept their organisation at the back.
Mahrez could well have grabbed his hat-trick just inside the hour, but the midfielder couldn’t get his shot from just inside the area anywhere near Gazzaniga’s goal.
A double change from Koeman saw Long and Filip Djuričić introduced and the latter almost helped get his side back into the game.
His pass found Mané in space, who looked to curl the ball over Schmeichel, only to see the Danish goalkeeper make a flying stop to tip it over the bar.
The hosts were not just going to settle for two however, and they almost added a third minutes after Schmeichel’s save. Marc Albrighton’s cross found an unmarked Esteban Cambiasso, but the Argentine dragged his shot just wide of the near post.
Former Saint Dean Hammond came on for the hosts to shore things up, and Nigel Pearson's side did just that to seal all three points in their battle for survival.
Saints will look to get back to winning ways when Aston Villa visit next weekend, knowing Tim Sherwood’s side could stop them qualifying for Europe if they finish seventh in the table.
Leicester City: Kasper Schmeichel, Wes Morgan (c), Robert Huth, Marcin Wasilewski, Riyad Mahrez, Marc Albrighton, Jeffrey Schlupp, Matty James (Danny Drinkwater 13), Esteban Cambiasso, Jamie Vardy (David Nugent 70), Leonardo Ulloa (Dean Hammond 77).
Unused Substitutes: Mark Schwarzer (GK), Ritchie De Laet, Paul Konchesky, Andrej Kramaric.
Goals: Mahrez (7, 20)
Booked: Wasilewski (81)
Southampton: Paulo Gazzaniga, Nathaniel Clyne, José Fonte (c), Toby Alderweireld, Ryan Bertrand, Harrison Reed, Victor Wanyama, Eljero Elia (Shane Long 66), Steven Davis (Filip Djuričić 66), Sadio Mané, Graziano Pellè.
Unused Substitutes: Kelvin Davis (GK), Maya Yoshida, Florin Gardos, Matt Targett, Sam Gallagher.
Referee: Roger East
Attendance: 31,939 (3,265 away fans).