Southampton recorded their first home victory over Chelsea since 2013, coming from behind to stun the Blues at a raucous St Mary’s.
Trailing to Raheem Sterling’s opener midway through the first half, Saints responded emphatically to lead before the interval.
Eighteen-year-old Roméo Lavia struck the equaliser with his first goal in senior football, an unerring 20-yard shot that curled inside Édouard Mendy’s near post.
Then Adam Armstrong ended his near 10-month wait for a goal to round off a sweeping Saints move in the last minute of the half.
Mohamed Elyounoussi and Mohammed Salisu both went close to extending the lead after the break, but Saints defended manfully to take maximum points from a breathless encounter.
Ralph Hasenhüttl made two changes to his starting line-up, with Romain Perraud returning from injury and Ibrahima Diallo making his first Premier League start of the season, as Moussa Djenepo and Joe Aribo dropped to the bench.
With another 30,000-plus attendance inside St Mary’s, the atmosphere under the lights added an extra dimension to the opening exchanges.
James Ward-Prowse sent a couple of early corners swirling in under Mendy’s crossbar, twice forcing Thiago Silva into important defensive headers.
At the other end, Gavin Bazunu’s handling was up to scratch from a Sterling cross that was floated into an awkward area, before Sterling latched on to a pass from Mason Mount and jinked inside to force Bazunu into the first save of the night, low to his right, though the England international will feel his shot ought to have carried more venom.
The summer signing was a constant menace, evading Perraud via a sharp one-two and crossing low towards Kai Havertz, only for Salisu to make a crucial sliding intervention.
Then it needed a similar piece of last-ditch defending from Salisu’s centre-back partner, as Armel Bella-Kotchap halted Sterling in full flight when he had Havertz in space to his left.
But the serial marksman was not to be denied, as Sterling added to his century of Premier League goals with the ninth of his career against Saints midway through the first half.
When Havertz played the ball across the box, Sterling was temporarily held up by a combination of Perraud and Bazunu, but kept his composure, delaying slightly before carefully rolling the ball into the gap to the keeper’s right.
Having been under the cosh in the minutes leading up to the goal, Saints’ response was impressive.
Behind for only five minutes, the hosts came roaring back with a sublime equaliser from Lavia following another Ward-Prowse corner.
Ironically, this was the skipper’s worst delivery, low and easily cleared, but only to the teenage midfielder, who was ready and waiting on the edge of the box.
Taking a touch to set himself, Lavia whipped a brilliant right-footed shot that started outside the post and curled around Mendy’s dive, brushing the keeper’s fingertips on its way into the net.
All of a sudden Saints had their tails up, as St Mary’s was whipped up into a frenzy. Elyounoussi’s sweeping ball out to the left deceived César Azpilicueta, who was beaten to it by Armstrong.
Just for a moment it seemed as if there was a chance for the striker to try his luck as the ball bounced up invitingly, but the angle was against him and the chance fizzled out.
Armstrong was not so shy in pulling the trigger soon after, but his low shot was comfortably dealt with by Mendy.
Perhaps his confidence was growing, and it hit a crescendo on the stroke of half time when a sweeping Saints move turned the game on its head.
Diallo started it from the right, feeding the ball into Ward-Prowse 30 yards out in a central position. Without the space to go for goal, the skipper wisely kept the ball moving to his left, where Perraud was waiting to cross first time for Armstrong, who gleefully rifled home from 12 yards to round off a superb team goal.
Chelsea were rattled, and Jorginho in particular. Having just been flattened by Diallo, the Italian was further enraged when clipped by Ché Adams, who playfully dinked the ball against him as he lay on the turf.
Referee Michael Oliver, who was doing his best to let the game flow, immediately blew for half time, further frustrating the visitors as he turned a blind eye to Jorginho’s histrionics.
This was a pulsating game that continued to ebb and flow into the second period.
Perraud, giving Saints natural balance down the left side on his return to the team, threatened to double his assist tally with a delicate chip to the far post for the onrushing Elyounoussi, who threw himself at the ball with a diving header that was destined for the net, only for Marc Cucurella to make a crucial block.
As Elyounoussi climbed to his feet, he was immediately presented with another chance as Adams knocked the ball down, and the Norwegian did well to improvise and hit the target once more, but was unable to generate enough power to beat Mendy.
Saints were dealt a setback on the hour when goalscorer Lavia departed with an injury, as Aribo came on and Ward-Prowse dropped back into a deeper role.
In the opposite dugout, having already replaced Ruben Loftus-Cheek at half time, Thomas Tuchel made a triple change on 66 minutes, introducing Ben Chilwell, Christian Pulisic and Armando Broja.
Broja, naturally a familiar face to Saints fans, was straight into the action as he twisted and turned his way into a crossing position, bamboozling Salisu in an early statement of intent on his St Mary’s return.
Perraud’s impressive return to the fold lasted 73 minutes, as the arrival of Djenepo from the bench afforded the Frenchman a breather, before Saints sensed a third goal.
In Ward-Prowse’s delivery, Saints pose a constant set-piece threat, and another of the skipper’s corners was met by Salisu, whose downward header was somehow denied by the most casual of clearances from Silva, who used his heel to keep the defender at bay.
As it was, the lead remained a precarious one into the closing stages, and Broja was determined to have his say, rising to meet a cross to the far post with a header clawed out by Bazunu at his near post.
With five added minutes to endure, it was a nervous finale for Hasenhüttl, who was pacing around his technical area, but Armstrong’s first goal since last November ultimately proved decisive.