Southampton banished the memory of their 9-0 defeat to Leicester back in October and moved six points clear of the relegation zone with a well-deserved 2-1 victory at the King Power Stadium.
Leicester midfielder Dennis Praet opened the scoring in the 14th minute but Stuart Armstrong's deflected effort (19) ensured Southampton, who hit the crossbar twice late in the first half through Danny Ings, went in at the break level.
Saints thought they'd been awarded a penalty when Shane Long went down in the area in the 64th minute, but VAR determined that the Irishman was offside before he broke into the box.
Ralph Hasenhuttl's side were not to be denied though, and they eventually took the lead in the 81st minute as Ings finished past Kasper Schmeichel to continue his fine run in front of goal.
With time ticking away, Jonny Evans appeared to grab a late leveller to seemingly deny Saints their revenge, but a VAR check showed Evans was offside as Southampton held on for what could prove to be a crucial victory.
How Saints gained revenge at Leicester…
Southampton took advantage of a slow start from Leicester as Ings had two early opportunities to break the deadlock. However, Schmeichel came to his side's rescue not once, but twice and he made himself big to deny Saints' in-form striker on both occasions.
Leicester: Schmeichel (7), Pereira (6), Soyuncu (6), Evans (7), Chilwell (5), Barnes 95), Praet (7), Choudhury (6), Maddison (5), Perez (6), Vardy (6).
Subs: Iheanacho (6), Gray (6), Tielemans (6).
Southamptom: McCarthy (8), Soares (7), Stephens (7), Bednarek (7), Bertrand (7), Redmond (8), Ward-Prowse (7), Hojbjerg (6), Armstrong (7), Ings (8), Long (7).
Subs: Adams (7), Djenepo (6).
Man of the match: Danny Ings.
Despite their sluggish start, it was Leicester who took an early lead. Quick thinking from Ayoze Perez released Jamie Vardy down the left and the striker produced an inch-perfect cross to Praet, who finished at the far post to score his first goal for the club.
However, Armstrong made sure there would be no repeat of October's hammering as his shot took a wicked deflection off James Maddison, wrong-footing Schmeichel to bring the scores level just five minutes later.
Schmeichel was called into action soon after, palming away a first-time half-volley from Pierre-Emile Hojbjerg that bounced awkwardly in front of him before Vardy correctly had a goal ruled out by VAR for offside.
Things could have got even better for Southampton heading into the interval, but the crossbar came to Leicester's rescue, denying Ings twice in as many minutes. First, he got to Armstrong's cross at the near post, touching the ball into the ground, past Schmeichel and onto the crossbar before producing an instinctive shot from just inside the penalty area which thundered back off the woodwork.
After the break, Caglar Soyuncu cleared a Jack Stephens shot off the line in the 47th minute and just after the hour the Saints thought they had won a penalty when Shane Long was clipped in the area by the Turkey international, who was also given a yellow card by referee Lee Mason.
However, Long appeared to be offside in receiving a through ball, with Soyuncu protesting his innocence, and after 90 seconds it was determined the Southampton striker was marginally ahead of Soyuncu, leading to the penalty decision and the yellow card being overturned.
Minutes later VAR also ruled out substitute Kelechi Iheanacho's clever back-heeled strike as Leicester's frustrations continued.
Then came the crucial moment. Nine minutes from time Ings, who was played in by Che Adams, scored the goal his efforts deserved, slipping the ball between the legs of the onrushing Schmeichel for his 14th league goal of the season.
Leicester boss Brendan Rodgers made two changes for the King Power clash with Southampton following his side's 1-1 midweek draw with Aston Villa in the Carabao Cup. Rodgers dropped Christian Fuchs and benched Youri Tielemans, bringing in Harvey Barnes and Hamza Choudhury.
After making wholesale changes for the Saints' 2-0 FA Cup win at home to Huddersfield last weekend, boss Ralph Hasenhuttl reverted primarily to the line-up that beat Spurs 1-0 on New Year's Day. The one change from that game saw Shane Long replace the benched Moussa Djenepo.
Ings was then brilliantly denied by Schmeichel, while Iheanacho's powerful drive was kept out by McCarthy as time ticked away.
But there was still time for more drama - more VAR drama to be precise. In the 90th minute, Jonny Evans thought he'd rescued a point after heading Maddison's free-kick beyond McCarthy, but VAR ruled out the goal for offside against the Northern Irishman.
Saints held on for what was their fourth Premier League win in five games, while defeat means Leicester suffered back-to-back league defeats at the King Power Stadium.
What the managers said...
Leicester manager Brendan Rodgers: "We are disappointed, but over the course of the game we didn't play well enough, that was pretty clear. Southampton deserved the win and it was a good three points for them.
"Over this period we have played a lot of games but if you want to develop as a squad and team you need to have that robustness. That is something players will develop because if you want to be successful you have to play lots of games."
Southampton manager Ralph Hasenhuttl: "We used it [the 9-0 defeat in the reverse fixture]. We showed the scenes. We didn't want to have revenge, we wanted an answer for ourselves and to show how far we are compared to the first clash. We can see this is a completely different team. The belief is absolutely great and the way we play football with the right balance of taking risk and working against the ball.
"Preparing for such a game it's a special week and we used all the time to find the right balance of not getting too motivated and sticking to the gameplan. What we have done in the last two or three weeks is amazing."
Man of the match - Danny Ings
It looked like it wouldn't be Ings' day as he twice hit the woodwork in the first half, but he worked tirelessly and was rewarded with the late winner.
Ings has scored 40 per cent of his Premier League goals this season (14/35) and is the highest-scoring player for Saints in a single Premier League season since Jay Rodriguez in 2013/14 (15). At this rate he could score plenty more.
- Southampton remain unbeaten in their last four away Premier League games against Leicester City (W2 D2), winning back-to-back such matches for the first time in the competition.
- Leicester have lost consecutive home Premier League games for the first time under Brendan Rodgers, having lost just one of their opening 14 such matches under him in the competition (W10 D3 L1).
- Southampton are the first side to concede 10+ goals against a specific opponent (Leicester City) in a single Premier League season since Everton did so against Arsenal in 2017-18 (10).
Live Renault Super Sunday
Southampton take on Wolves at St Mary's next Saturday afternoon; Kick-off 3pm. Meanwhile, Leicester travel to Burnley next Sunday, live on Sky Sports; Kick-off 2pm.