Could have spent the opening 40 minutes in dressing gown and slipper for all the difference it would have made. But kept his concentration to make a fine point-blank save from Koscielny at 1-0 and showed good reflexes after the break.
Has had tougher battles on the training ground than he had on the pitch tonight. Kept a tight rein on Giroud, instigated attacks with crisp passing and scored the crucial opener when he rose high above Monreal at the back post and headed past Szczesny.
Got chalk on his boots on the right flank as he romped forward at every opportunity from his advanced right-back role.
Slotted in well in central defence in the first half but looked less at ease when Arsenal stepped it up after the break.
There were plenty of outstanding contributors in red but none was better than the teenage left-back. Set up the opener with a fabulous cross and his every touch, run and move shimmered with class and confidence. Drew a brilliant save from Szczesny late on.
Ferocious work ethic from the midfielder, who closed down the space diligently and used the ball sensibly.
Unhurried, calm and completely controlled display from the elegant midfielder in front of the Southampton defence.
Epitomised the energy and endeavour of his team.
'Adam Lallana, he's off to Brazil' sang the home fans in support of their captain, whose touch, intelligence and clever runs caused continuous problems to the Arsenal defence.
In his first league start, the attacking spearhead made a valuable contribution with his physical presence but lacked the composure required when he slammed a sitter wide in the first half. Got a standing ovation when he was subbed.
At the heart of many of Southampton's attacks, but not at his most influential. Moved into the centre-forward role for the last half-hour.
Had a few brain farts, and inexplicably beaten at his near post for Southampton's opener, but made some brilliant saves and controlled his box well.
In one of his toughest assignments of the season, the big German had to be at his most durable to limit the damage to his team.
The contract rebel could be forgiven for yearning for semi-retirement in the French league after 90 minutes against the unstoppable force that is Luke Shaw. Suffered a pasting at times, but kept his head above water and instigated Arsenal's comeback by creating the equaliser.
Got the nod over Gibbs but may soon lose his place following a mixed display. Beaten too easily in the air by Fonte at the far post for the opening goal.
Made a brilliant interception to keep out a goal-bound Gallagher shot at 1-0 on a night when he had to frequently cover for the mistakes of those in front of him.
Flitted in and out of the game but was more involved after the break and his snap-shot from the edge of the box put Arsenal 2-1 up.
In the monsoon conditions, at times looked like he was running through a foot of mud. Raised his game after the break but his passing lacked snap and precision as the Saints closed down the space in which he usually operates so smoothly.
Tore his hair out at the lack of covering from Arsenal's attacking midfielders. His commitment and communication were unquestionable but his partnership with Arteta is too one-dimensional. Sent off late on for a needless two-footed lunge on Lallana.
Had a few powerful runs but was isolated on the right flank and struggled to get involved. Subbed midway through the second half.
Anonymous in the first half and, although he was more involved after the break, when he assisted Cazorla's goal, his lack of tracking back and closing down harmed his team.
Got precious little service but always provided an outlet and delivered the faintest of touches to Sagna's cross to launch the Gunners' comeback.