London - Alexis Sanchez's late strike saw Arsenal edge Premier League top-four rivals Southampton 1-0 on Wednesday as Arsene Wenger's side closed to within two points of the Champions League places.
The Chilean forward netted his 14th goal of the season in the 89th minute by slotting home from Aaron Ramsey's pull-back to puncture a bubble of growing frustration at the Emirates Stadium.
It was cruel on visiting goalkeeper Fraser Forster, who had produced excellent saves to keep out Danny Welbeck and substitute Olivier Giroud in the second half.
The last-gasp victory moved Arsenal above Swansea City into sixth place, two points behind fourth-place Manchester United, while Southampton remain third after back-to-back losses.
Following Southampton's 3-0 home defeat by defending champions Manchester City on Sunday, there was a degree of pressure on Ronald Koeman's side to prove their top-four credentials.
Would an impressive start to the season turn into a collapse, or was it only a blip?
The opening 45 minutes in north London suggested the latter and Koeman would have been the happier manager as he began his half-time team talk.
Nonetheless, Arsenal created the first chance of the game in the seventh minute.
Welbeck, fresh from his weekend winner at West Bromwich Albion, was sent clear down the left by a precise through ball from Santi Cazorla, but he slotted wide of the target.
The visitors then suffered a blow when Jack Cork appeared to roll his ankle following a challenge from Ramsey. The midfielder struggled on until the 29th minute, when he was replaced by Maya Yoshida.
By that time, Southampton had missed the best chance of the first half courtesy of main striker Graziano Pelle.
The Italian had scored nine goals in his first 16 appearances for the south coast outfit, yet he lacked the composure to finish off a fine move.
After playing a neat one-two with Steven Davis on the edge of the penalty area, he blazed over with his left foot from 12 yards.
Arsenal were jittery in front of their increasingly frustrated fans, lacking cohesion and confidence in their play despite enjoying plenty of possession in midfield.
Alex Oxlade-Chamberlain saw a 15-yard shot well handled by Forster after slick build-up play by Cazorla and Ramsey, before Welbeck had a header brilliantly tipped over by the England goalkeeper.
Koeman's side always looked a threat on the counter-attack, with Shane Long wasting a decent opportunity when he fired over early in the second period.
The Emirates faithful were getting ever more nervous and boos rang around the ground in the 65th minute when Wenger opted to introduce French striker Giroud for the ineffective Oxlade-Chamberlain.
The change almost paid dividends within three minutes as Giroud collected Sanchez's diagonal pass before seeing a left-foot drive beaten away by Forster.
Sixty seconds later, Celtic's former number one was pressed into action again. This time, Forster produced a superb one-handed save to push Welbeck's effort to safety.
Giroud made a big impact off the bench and he forced Forster into a clawing save with minutes remaining.
But Arsenal kept searching for the winner, which came with a minute of normal time remaining and with Southampton down to 10 men after Toby Alderweireld limped off, Koeman having already used all his substitutes.
After Giroud caused havoc in the Southampton box, Ramsey collected the loose ball and crossed from the right for Sanchez to beat Forster from close range.