Jan Bednarek's goal saw Southampton beat Arsenal 1-0 to inflict further damage on the Gunners in their quest to finish in the top four.
2021/2022 Premier League
1-0
Match Report
The Gunners knew a victory would move them level on points with rivals Tottenham, who lost 1-0 at home to Brighton earlier in the day, but they could not find a way past Forster.
Bednarek gave Southampton the lead a minute before half-time after the Saints 'keeper had brilliantly denied Bukayo Saka from scoring early on.
The 34-year-old then made a string of fine saves in the second half, with Arsenal striker Alexandre Lacazette missing after testing positive for Covid, to give the hosts their first victory in six matches.
How Forster denied Arsenal
Gabriel Martinelli forced the first save from Forster in the ninth minute when he cut in from the right and sent a bending shot towards the far corner which the goalkeeper parried away.
But Forster's best stop - and perhaps of the season - came from a Southampton mistake inside their own half. Yan Valery telegraphed his pass into Lyanco allowing Eddie Nketiah to intercept and he moved the ball out to Martinelli, who crossed for Saka but his close-range effort was wonderfully pushed behind by the right hand of Forster.
Nuno Tavares returned to the Arsenal team at left-back for the first time since he was hauled off at half-time against Crystal Palace earlier this month. He had a solid 70 minutes and drew two fouls in the Southampton final third during the first half, the second resulting in Cedric Soares firing the set piece over when crossing into the box was the better option.
Arsenal dominated possession with Southampton unable to launch any meaningful counter-attacks in their new-look 3-4-3 formation, but they grabbed the opener a minute before half-time through an unlikely source. Arsenal cleared James Ward-Prowse's corner but then switched off when it was recycled into the area by Romain Perraud. Mohamed Elyounoussi turned the ball back for Bednarek, who finished coolly first time as Ramsdale got a hand to it but could not keep it out.
Arsenal have won just four points from losing positions this season - only Wolves (3) have taken fewer - and at the start of the second half it was clear the trend was set to continue. Perraud was denied making it two by an excellent block from Ben White after burrowing his way into the area.
Emile Smith Rowe's introduction on the hour was much-needed for Arsenal with the midfielder instantly breaking onto a loose ball in the Southampton area but saw his shot blocked by Martinelli.
Then Smith Rowe was brilliantly denied by Forster as the Southampton 'keeper clawed away his close-range volley before he saved again from Saka which led to Martin Odegaard firing the follow-up wide. There was still time for Forster to push away a curling effort from Granit Xhaka late on.
Match Events
0' The match is about to start!
16' MISS! Saka's shot stopped
26' CHANCE! Armstrong's shot saved
37' Cedric's free-kick over the bar
43' GOAL! Southampton 1-0 Arsenal (Bednarek)
55' Yellow Card! Broja booked
59' Sub! Smith Rowe replaces Cedric
73' CLOSE! Smith Rowe's shot stopped
81' CHANCE! Odegaard's shot wide out
Line-ups
Southampton XI: F. Forster, Romeu, Armstrong, M. Elyounoussi, Ward-Prowse, Bednarek, Perraud, Lyanco, Walker-Peters, Valery, A. Broja
Subs: Shane Long, Caballero, Redmond, Stephens, A. Armstrong, Adams, N. Tella, V. Livramento, Mohammed Salisu
Arsenal XI: Xhaka, Cedric, Martin Odegaard, Gabriel, Ramsdale, B. White, Nketiah, A. Lokonga, Martinelli, Nuno Tavares, Saka
Subs: Leno, M.Elneny, Pepe, Holding, Smith Rowe, Z. Swanson, M. Azeez, M. Ogungbo, O. Hutchinson