Fabian Delph hit a spectacular late winner as Aston Villa ended Southampton's unbeaten home record in an entertaining match at St Mary's.
The midfielder unleashed an unstoppable 25-yard drive into the top corner for his first Premier League goal.
Gabriel Agbonlahor had slotted Villa ahead after a slick counter-attack, but Jay Rodriguez nodded in a leveller.
Lambert hails 'massive' Villa victory
Headers from Villa's Libor Kozak and Saints' Dani Osvaldo cancelled each other out before Delph's superb strike.
Saints may feel hard done by after bossing the game for large periods, but Delph's sublime finish 10 minutes from time was a worthy winner.
The result also vindicated Villa manager Paul Lambert's decision to drop star striker Christian Benteke, who had gone seven games without a goal, as the Belgian's replacement Kozak got on the scoresheet.
Lambert's side have excelled on the road this campaign, with Chelsea inflicting their sole defeat back in August, and their third away win was achieved through dogged defending and clinical finishing.
The injury-hit Saints also made a fine contribution to a topsy-turvy contest, but they were made to pay for some sloppy defending, and a run of three straight defeats threatens to undermine their fine start to the season.
Aston Villa's third away win of the season means they have now accrued 12 of their 19 Premier League points on the road.
The home side made a lively start and almost took the lead when Adam Lallana's cross ricocheted onto the crossbar, but they were hit on the break when Villa took the lead with their first attack.
Delph won the ball just outside his own box and set free Agbonlahor, who evaded Dejan Lovren's desperate lunge before dinking home an excellent first goal of the campaign.
It was only the third time Saints had conceded at home all season, and the hosts' confidence did not appear dented as they continued to monopolise possession and create goalscoring opportunities.
The best of them was a powerful Rodriguez header that was palmed away by Brad Guzan, but just after the break Saints levelled with an almost identical attack - Rodriguez guiding home Nathaniel Clyne's inviting cross from the right.
Saints will bounce back - Pochettino
The equaliser sparked a flurry of Saints chances as their domination continued, but Villa again went ahead against the run of play when the home side cheaply conceded possession.
Karim El Ahmadi won the ball from Jack Cork on the right wing and whipped in a cross for Kozak to head home.
Five minutes later, Cork atoned for his earlier lapse with an excellent deep cross that Lambert headed back across goal for Osvaldo to nod in from close range.
But Villa regained the lead for a third - and final - time in sensational style as Delph ran unchallenged through the centre of the pitch before giving Saints keeper Paulo Gazzaniga no chance.
Southampton manager Mauricio Pochettino:
"It is a difficult result to take because the team put in a great effort and did very well.
"It's the type of game you lose maybe once in 1,000, but tonight we lost it.
"We were made to pay for some bad defending. They created four chances and scored three goals, whereas we created 21 chances and scored twice.
"We were unlucky, but we also made mistakes."
Aston Villa manager Paul Lambert on Christian Benteke:
"The football club does not revolve around one player. Christian was brilliant last year, but has had a little spell when he has not been hitting the heights of last year.
"But when he came on I thought he looked as if he was getting back to the powerhouse he is. Sometimes a rest is as good as playing.
"We needed three points and I thought we were lethal in front of goal.
"I thought Agbonlahor's goal was world class - when he is like that with his speed and power there are not many people can catch him."
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