Arsenal kept alive their hopes of qualifying for Europe as Eddie Nketiah punished a howler from Southampton goalkeeper Alex McCarthy to inspire a much-needed 2-0 win on Thursday.
Mikel Arteta's side were handed the opener in the first half at St Mary's when Nketiah picked off McCarthy's pass and fired home.
Joe Willock doubled Arsenal's lead late in the second half, moments after Southampton's Jack Stephens was sent off for bringing down Pierre-Emerick Aubameyang.
Arsenal had suffered two successive defeats following the Premier League restart after the coronavirus hiatus.
That wretched run effectively ended their bid to reach the Champions League and sparked criticism of Arteta's decision to give new contracts to David Luiz and Cedric Soares despite their problems with poor form and injuries respectively.
Against the dispiriting backdrop, Arsenal's success at St Mary's, which lifted them into ninth place and kept them in the hunt for a Europa League berth, was a welcome tonic for Arteta.
Arsenal had kicked off with 40 points, which ranked as their joint lowest tally after 30 games of a Premier League campaign.
Matteo Guendouzi was dropped just days after reports that Arteta has grown frustrated with the French midfielder's behaviour, while Alexandre Lacazette and Mesut Ozil were left on the bench.
Guendouzi reportedly taunted Brighton players about how much he earns during Saturday's match and clashed with Seagulls striker Neal Maupay after the final whistle, with his absence at St Mary's put down to "squad management" by Arteta.
Despite all the turbulence around Arsenal at present, they started brightly in scorching hot temperatures on the south-coast.
Aubameyang should have put Arsenal ahead early on but, after racing into the penalty area, the Gabon forward's close-range shot cannoned off the bar and bounced clear.
The Gunners were making all the running and their pressure was rewarded in the 20th minute thanks to the gift from McCarthy.
Chasing down Jan Bednarek's ball to McCarthy, Nketiah forced a woefully misdirected pass from the Saints keeper, pounced on the loose ball and slotted into the empty net.
It was the 21-year-old's second Premier League goal of the season and his fourth in all competitions for the Gunners after a loan spell at Leeds.
Arsenal had blown the lead at Brighton and have a poor away record this season, so alarm bells were ringing when Southampton striker Danny Ings was left unmarked to volley over.
Southampton were pushing hard and Ryan Bertrand fired into the side-netting from a tight angle before Shane Long forced a good stop from Emiliano Martinez.
But Stephens saw red for his foul on Aubameyang on the edge of the area and Willock slotted home from close-range to seal the points in the 87th minute.
In Thursday's other early kick-off, Burnley beat struggling Watford 1-0 thanks to Jay Rodriguez's goal.
Sean Dyche's team took the lead in the 73rd minute when Rodriguez got across his man at the near post and stooped to head in Dwight McNeil's cross.
Burnley, rocked by speculation Dyche might quit at the end of the season, remain in mid-table, while Watford are just one point above the relegation zone.