Just three days after losing 1-0, goals from Nicolas Pepe, Bukayo Saka and Alexandre Lacazette saw the Gunners claim all three points to lift them to eighth in the Premier League table.
It started so well for Southampton, who led through Stuart Armstrong’s early strike but the defeat sees Ralph Hasenhuttl’s side slip into the bottom half of the league standings.
Southampton made three changes from that FA Cup win on the weekend, two of them enforced, as Yan Valery and Jake Vokins came in for Kyle Walker-Peters and Ryan Bertrand who were injured and suspended, with Alex McCarthy returning in goal.
Arsenal, meanwhile, made five changes themselves. David Luiz, Thomas Partey, Emile Smith-Rowe, Saka and Lacazette all came in as Mikel Arteta’s side looked to return to winning ways.
The Gunners broke through the Saints defence within the opening minute. Lacazette was played through on goal by Smith-Rowe, but McCarthy came out brilliantly to save with Jan Bednarek then doing well to clear and prevent the Frenchman from a tap in on the follow up.
It proved to be an exciting start at St. Marys, with Valery then doing well to break down the right before he whipped the ball in and picked out Danny Ings at the front post, but Rob Holding got across to block his glancing header inside the third minute.
And it was from that corner that Southampton went in front with a routine from the training ground. Armstrong started his run on the edge of the area and James Ward-Prowse, making his 300th appearance for the Saints, picked him out just inside the box and Scotsman fired the ball past Bernt Leno with a fine first-time strike.
But the Gunners drew level in only the 8th minute. Granit Xhaka found room and threaded the ball through to Pepe, who stayed onside and one on one with McCarthy stroked it across the keeper and into the far corner.
And the visitors nearly went ahead shortly after in spectacular fashion when Valery headed Saka’s cross as far as former Saint Cedric Soares on the edge of the area, but his volley curled just wide of the top corner.
Southampton were having some joy from set plays, with Ward-Prowse picking out Ings with a free kick from the left but the striker’s effort on the volley went straight at Leno from inside twelve yards.
Chances continued to come at both ends. Vokins, making his first league start of the campaign, was found by Ibrahima Diallo in space on the left, and his great ball in picked out Che Adams but his firm header was palmed away by the diving Leno.
Good build up play from the Saints then saw Ings release Valery down the right hand side after a neat touch from Adams and the full back cut inside into the area, his eyes lit up, but he fired over the bar with his left-footed effort. Armstrong then flashed an effort wide of the far post as the hosts continued to create chances – but with no reward inside the opening half an hour.
Gunners turn it around
But it was Arsenal who went in front seven minutes before the break. Lacazette slipped the ball through to Saka, who got there ahead of McCarthy to take the ball around him before firing into the empty net from the edge of the penalty area.
The Saints had a chance to draw level five minutes after half time when Adams found Theo Walcott on the edge of the area, but his rasping effort went straight at Leno as he looked to score against his former club.
Smith-Rowe then saw an effort cleared off the line by Jack Stephens before Pepe couldn’t convert Hector Bellerin’s low cross from the right as the game continued its end-to-end flow in the first part of the second half.
As the half grew on, Saints saw more of the ball as they looked to get back into the game but were met with a resilient Arsenal defence. A moment of magic from Ings as he skipped past several challenges saw him met by Leno, with the German doing well to smother the ball at the striker’s feet midway through the half.
However, it was the Gunners who extended their lead after 73 minutes. Cedric played a sublime cross-field ball to pick out Saka in space on the right hand side and he played the ball across to Lacazette who from close range fired in his eighth league goal of the season.
With four minutes to go young substitute Caleb Watts won a free-kick right on the edge of the area, but Ward-Prowse saw his effort turned away by the diving Leno as Saints’ run of three home wins in a row came to an end.