Southampton were denied a first league win at Arsenal since 1987 by two late goals as the Gunners salvaged a 3-3 draw at Emirates Stadium.
Leading 3-1 with two minutes of normal time remaining, Saints were hit by quick-fire strikes from Martin Ødegaard and Bukayo Saka to leave a point earned against the odds feeling more like a defeat.
Saints had stormed into a 2-0 lead inside 14 minutes, including a goal after 28 seconds from Carlos Alcaraz, who then set up Arsenal old boy Theo Walcott to double the advantage.
Gabriel Martinelli pulled one back for the hosts, who dominated the rest of the first half and much of the second period, only to be hit by a sucker punch from a 67th-minute corner as substitute Duje Ćaleta-Car headed Saints 3-1 in front.
The visitors looked likely to hold on as Arsenal appeared to run out of steam until Ødegaard threw them a lifeline, before Saka instantly equalised, leaving Saints having to see out eight agonising minutes of added time just to take home a point.
Rubén Sellés made three changes to his side after the home defeat to Crystal Palace, with the on-loan Ainsley Maitland-Niles ineligible to face his parent club.
Elsewhere, Joe Aribo and Kamaldeen Sulemana dropped to the bench, as Romain Perraud, Mohamed Elyounoussi and Adam Armstrong were recalled to the starting line-up.
Perhaps part of the plan behind the inclusion of Armstrong was his extra energy to press Arsenal, which was evident from the very first minute.
When the ball was played back to Aaron Ramsdale, the goalkeeper was rushed into passing it out straight to Alcaraz, who still had plenty to do.
Receiving the ball 25 yards from goal, the attacker whipped his shot away from the diving shot-stopper, who got fingertips to the ball but could not prevent it nestling in the back of his net via his right-hand post.
The home crowd was stunned, with the goal timed at 28 seconds, but their team responded like a wounded animal, tearing forward, undeterred by the early setback.
Despite plenty of attacking intent, chances were not forthcoming, and the Emirates was plunged into near silence when Walcott doubled Saints’ lead after 14 minutes.
Again Alcaraz was at the heart of it, driving forward and playing a perfect pass in behind the defence for Walcott, who slotted home first time, passing the ball back across Ramsdale and into the bottom corner from ten yards.
Walcott spent 12 years as an Arsenal player, racking up nearly 400 appearances, and did not celebrate the goal, but its significance was potentially seismic at both ends of the Premier League table.
Saints had already weathered one storm, having scored first in the game, and now they had to do it again against a home team determined to show their true colours.
After left-back Oleksandr Zinchenko fizzed a low ball across goal that went untouched, Saka had more luck from the opposite flank, driving to the byline and delivering a cross impressively dispatched by Martinelli on the volley from 15 yards.
Now the home fans had really found their voice and roared their team on, expecting more of the same.
Instead there were more nervy moments at the back, as Perraud floated a cross to the far post where Elyounoussi was waiting.
The Norwegian’s header was on target but lacked power, yet Ramsdale was unconvincing, parrying the ball into the air and only as far as Alcaraz, whose return volley forced a more orthodox save.
This was a breathless half of football, but Arsenal were just getting started. When Martinelli crossed for Ødegaard, the captain ought to have done better than head wide from ten yards.
The wide players, Martinelli and Saka, were major threats from every attack. Alcaraz and Perraud both went into the book for bringing down the England man, while Kyle Walker-Peters later followed for a similar offence on the Brazilian.
Meanwhile, Saints were forced to survive seven added minutes at the end of the first half due to a lengthy stoppage play following a nasty fall for Jan Bednarek, who appeared to land on his head after an aerial challenge with Martinelli.
After a lengthy delay, the Pole was adamant he could continue, but the decision was taken out of his hands by Saints’ medical team, with Ćaleta-Car summoned from the bench to take his place for the final five minutes of the half, plus the extended period of added time.
There were a couple of alarms before Saints could regroup at the interval, as Saka’s pass through to Gabriel Jesus forced Gavin Bazunu from his goal line, smartly shutting down the angle to concede a corner.
From the resulting delivery, Ben White’s glancing header looped over the rooted Bazunu but Alcaraz was there, covering his goalkeeper on the line, to head the ball clear and preserve Saints’ lead.
Surprisingly, it was to be the Argentinian’s last contribution, as a tactical tweak at half time saw Sellés switch to a back five, with Alcaraz sacrificed for Lyanco to slot in as the right-sided centre-back.
Saints were camped in their own half for the majority of the second period, but Arsenal’s frustration was growing.
The hosts thought they had finally opened up the stubborn blue wall in front of them when Martinelli raced to the byline and crossed for Saka, but the ball had just gone out of play before Saka’s volley, which struck the post and stayed out in any case.
A rare foray arrived in the shape of a burst down the right from Walker-Peters, who fired the ball against the legs of a defender to win a corner.
This was Saints’ moment. James Ward-Prowse delivered, Armel Bella-Kotchap flicked on and Ćaleta-Car headed in, sparking jubilant scenes in front of the raucous pocket of travelling fans tucked away in the far corner of the Emirates Stadium.
Arsenal threatened to move within a goal of their visitors just three minutes after conceding, but Jesus could not keep his volley down as he stretched to steer in Martinelli’s floated ball.
The pressure remained, but the hosts seemed to have had the stuffing knocked out of them by Saints’ third, and their belief was visibly wavering on a night that could prove costly in their quest to land a first Premier League title since going undefeated in 2003/04.
Just as Arsenal looked beaten, Ødegaard traded passes with White and curled in a brilliant low shot from 20 yards to give the Emirates life once more.
Within two minutes, Reiss Nelson’s shot was parried by Bazunu and pounced upon by Saka, who tucked in the rebound in the 90th minute, with eight added minutes for Saints to hold out for a point.
Substitute Leandro Trossard thundered a shot against the top of the crossbar from the very next attack, while Nelson’s effort deflected inches wide before Saints somehow survived a last-gasp melee to leave north London with a point that looked, for so long, like being three.
Arsenal: Aaron Ramsdale, Rob Holding, Ben White, Oleksandr Zinchenko (Eddie Nketiah 72), Gabriel, Fábio Vieira (Leandro Trossard 57), Thomas Partey, Martin Ødegaard (c), Gabriel Martinelli (Reiss Nelson 85), Gabriel Jesus, Bukayo Saka.
Unused subs: Matt Turner, Jorginho, Jakub Kiwior, Reuell Walters, Kieran Tierney, Emile Smith Rowe.
Goals: Ødegaard, Martinelli, Saka.
Southampton: Gavin Bazunu, Kyle Walker-Peters, Jan Bednarek (Duje Ćaleta-Car 40), Armel Bella-Kotchap, Romain Perraud, Roméo Lavia (Ibrahima Diallo 86), James Ward-Prowse (c), Mohamed Elyounoussi, Theo Walcott (Kamaldeen Sulemana 77), Charly Alcaraz (Lyanco 45), Adam Armstrong (Paul Onuachu 77).
Unused subs: Alex McCarthy, Joe Arivo, Mislav Oršić, Stuart Armstrong.
Goals: Alcaraz, Walcott, Ćaleta-Car.