Substitute Sadio Mane inspired a stunning second-half Southampton fightback as they came from 2-0 down to beat Liverpool 3-2.
Liverpool looked to be cruising to victory at St Mary's as goals from Philippe Coutinho and Daniel Sturridge put them in control at the break.
But, boosted by the half-time introductions of Mane and Victor Wanyama, Saints came storming back.
Mane atoned for having a penalty saved by cutting the deficit in the 64th minute before Graziano Pelle struck a fine equaliser in the 83rd minute.
The comeback was complete moments later as Mane capitalised on indecision in the Liverpool defence to coolly finish past Simon Mignolet and spark wild celebrations amongst the home fans and Saints boss Ronald Koeman.
The dramatic victory sees Saints maintain their push for a European place while Liverpool have work to do in their final nine games to make up ground.
Fresh from signing a new long-term deal on Friday, Jurgen Klopp handed Jon Flanagan the captain's armband for the first time at St Mary's, with Jordan Henderson on the bench.
Jose Fonte returned for Southampton, who were aggrieved not to be awarded an early penalty when Shane Long went down in the box under a challenge from Dejan Lovren.
Pelle then volleyed a tricky chance over the bar, but it was Liverpool who took the lead after 17 minutes as Coutinho cut in from the left and hit a perfectly-curled strike across goal and into the far corner.
While there were questions over whether Fraser Forster should have saved it, there was nothing he could do about Liverpool's second shortly afterwards.
The visitors countered at pace, with Coutinho slipping the ball down the wing for Origi and the Belgian passing into the box for Sturridge, who bought a yard with a clever stepover and then finished well.
The double setback knocked the stuffing out of Saints and they were fortunate not to fall further behind when Joe Allen was through on goal but saw his shot saved by Forster.
The Saints keeper then blocked a low effort from Sturridge before Allen had a goal ruled out for offside.
Saints offered little threat before the break but the introductions of Mane and Wanyama gave them a much-needed lift.
They were handed a chance to cut the deficit from the penalty spot early in the second half as Martin Skrtel, who came on at half-time for Liverpool in place of Dejan Lovren, was penalised for grabbing Pelle's shirt.
Mane stepped up to take the penalty but saw Mignolet dive to his right and save.
Unflustered, Saints continued to press and they cut the deficit in the 64th minute when Mane held off Sakho in the box and fired into the corner.
Substitute Christian Benteke missed a fantastic chance to restore Liverpool's two-goal lead when he was played in by Adam Lallana but dragged his shot wide.
It would prove a costly miss as Saints snatched victory in the final 10 minutes.
Pelle equalised in the 83rd minute with a fine left-foot strike from just outside the box before Liverpool failed to clear their lines and were punished by Mane, who again finished well past Mignolet to snatch an unlikely three points.
Player ratings
Southampton: Forster (5), Martina (5), van Dijk (5), Fonte (5), Bertrand (6), Steven Davis (5), Romeu (6), Clasie (5), Tadic (6), Long (6), Pelle (7).
Subs: Mane (8), Wanyama (7), Ward-Prowse (6).
Liverpool: Mignolet (7), Clyne (6), Lovren (5), Sakho (5), Flanagan (6), Lallana (6), Allen (6), Can (6), Coutinho (7), Sturridge (7), Origi (7).
Subs: Benteke (5), Skrtel (5), Ojo (5).
Man of the match: Sadio Mane