Mikel Arteta is thrilled by the "incredible" maturity shown by Eddie Nketiah since his return to Arsenal, while he also reminded Bukayo Saka he has all he needs at Arsenal amid transfer speculation.
Arsenal had suffered back-to-back defeats to Manchester City and Brighton and Hove Albion following the Premier League's resumption earlier this month, with the Gunners falling well short of expectations.
But at St. Mary's they avoided a third consecutive loss, Nketiah opening the scoring in the first half when he charged down an Alex McCarthy pass and slotted into an empty net.
Joe Willock secured the win late on shortly after Jack Stephens was sent off, but it was Nketiah who made the biggest impression on Arteta.
"Eddie, since I joined, the maturity [he's shown] is incredible," Arteta told reporters. "I demand a lot from the forward players and they've done it.
"A lot of goals we score are because of the errors we force. In that heat it's not the nicest thing to do but it's important because it generates belief in what we do."
Another Arsenal product, Saka, also caught the eye. The 18-year-old has featured on the wing and at left-back in his first full season in the senior side, impressing in both roles.
On Thursday he featured in an advanced role and Arteta was impressed with his creativity.
However, the teenager's contract expires next year and there is growing concern he could opt to leave the Gunners, though Arteta believes he has everything he needs at Emirates Stadium.
"It [his future] in his hands," he said. "He has a manager who has total belief in him and team-mates who adore him.
"You can put him in different positions and he picks it up really quickly. He could have produced three goals today easily."
Arteta also addressed Arsenal's recent issues, insisting he noticed a difference in training before the game with Southampton.
"We had two very difficult weeks," he added. "I was concerned after the defeat at Brighton, it really touched the team, but I could see yesterday the reaction was really positive.
"We have to evolve as a team and there are a lot of things we have to go through to learn. They are so willing. I never criticise the effort, I was critical of the way we lost [at Brighton]."