Morgan Gibbs-White scored the only goal of the game to give Nottingham Forest their first win of the new Premier League season at Southampton.
His initial header was cleared by Yukinari Sugawara on the goalline but the Forest captain reacted quickly to tap in the rebound in the 70th minute.
Forest could have taken the lead in the first half but debutant Nikola Milenkovic shinned an effort wide from four yards.
Cameron Archer came within inches of equalising on his home debut for the Saints but he could not make contact on Charlie Taylor's ball across the face of goal.
Like in their opening day defeat by Newcastle, Southampton controlled the majority of the ball but failed to create many meaningful openings on goal.
Left wing-back Kyle Walker-Peters was a constant threat in the second half and forced a save from Forest keeper Matz Sels after cutting inside on to his right foot.
Russell Martin's Saints remain winless in their previous 15 Premier League matches and without a goal in their past two.
Saints face battle to remain in top flight
The Saints are back in the top flight after a year away but they are already facing a battle to maintain that status come May.
Martin’s side played brilliant possession-based football in the Championship last term and sticking to that this season will prove hugely difficult, as Vincent Kompany’s Burnley found out last year.
Southampton had two-thirds of the possession but had just one shot on target.
Martin spoke about the importance of scoring their first goal of the campaign to BBC Match of the Day: "We need that goal to relax everyone. I get it after the last time the team was in the Premier League but we're here now."
Ben Brereton Diaz has, so far, failed to threaten the goal but new signing Archer has looked lively in his two brief substitute appearances.
Despite bringing in new faces to their squad, the Saints have lined up in their opening two Premier League games with just two changes from the side who featured heavily last season.
Martin’s side face a trip to Brentford next with points needing to be picked up sooner rather than later.
Forest aiming for higher finish
Nottingham Forest were embroiled in a relegation battle during the whole of last season and survived the drop despite only accumulating 32 points.
A four-point deduction in March for breaching Premier League profit and sustainability rules added to a campaign of uncertainty, but the focus for manager Nuno Espirito Santo will now be on looking ahead.
Despite having less of the ball, Forest created the better opportunities with Ola Aina proving a constant threat on the left of the attack while captain Morgan Gibbs-White's dominated in the middle of the pitch and was rewarded with the game's only goal.
There is talent in attack for Forest with the likes of Anthony Elanga, Callum Hudson-Odoi, and Aina showing flashes of what they can do at St Mary's.
And with the addition of the combative Elliot Anderson from Newcastle in the centre of midfield, Forest now looks like a more settled outfit.
It has been an impressive start by Nuno's side with four points from a possible six and they welcome Wolves to the City Ground next Saturday.
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