Development squad downed by Saints.
Southampton U21 3 Sunderland U21 2
Kevin Ball's development squad kicked off the new season with a narrow defeat at Southampton.
Sam Hoskins opened the scoring early on for the hosts only for Jordan Laidler to level.
Calum Chambers re-establish Saints' lead just before the hour and Hoskins then added a second, but Laidler struck again to ensure a nervy finish for the home side.
Ball's starting line-up included a number of players who had played first-team football during pre-season, including defender Blair Adams and striker Ryan Noble.
Hoskins netted the opener after just 12 minutes with a crisp finish but the remainder of the first half was an even affair, with Billy Knott and Laidler coming close for the visitors while Hoskins had several opportunities to grab a second goal.
The lead would have been doubled early in the second half but for excellent work from John Egan, who got his body in the way of Jake Sinclair's effort to divert the ball onto the crossbar.
And just 60 seconds later Sunderland were level; Laidler holding off two defenders to drive a shot beyond Saints keeper Cody Cropper.
However, Sunderland couldn't build on the leveller as Calum Chambers headed in just after the hour before Hoskins fired home his side's third goal.
Ball's side set up a nervous last 16 minutes by reducing the arrears through Laidler, who tucked home after Louis Laing's driving run down the right.
But it was Southampton who came closest in the closing stages as Hoskins was denied a hat-trick by a fine save from Jordan Pickford.
Pickford, Laing, Egan, Ferguson (Joyce, 89), Adams, Lynch, Oliver (Gorrin, 70), Knott, Deacon (Mitchell, 66), Noble, Laidler.
Subs not used: Dixon, Callaghan.