Saints made it three wins from three in pre-season, as Jos Hooiveld's goal earned them a 1-0 victory at Swindon.
After triumphing against minnows EHC Hoensbroek and Sporting Hasselt on their summer tour, Ronald Koeman's side stepped up their preparations with a trip to the League One outfit.
The game was controlled by Saints throughout, but there was just the one goal, coming early in the second half from Hooiveld.
There was no place for Liverpool target Dejan Lovren, who was out with a slight knock, while Steven Davis was also missing through injury.
Saints started well and nearly led through new signing Graziano Pelle in the fourth minute.
Matt Targett slid a ball down the left wing for Lloyd Isgrove to chase, with his low ball picking out the Italian striker, only for his first-time strike to be blocked.
Nathaniel Clyne should have opened the scoring in the 12th minute, pouncing on a loose ball down the inside-right channel and driving into the area, but his powerful low strike was beaten away by Wes Foderingham.
Isgrove then had a sight of goal after 16 minutes, but curled a right-foot effort wide of the far post from just inside the area.
Swindon’s only real moment of any threat came in the 33rd minute, with Andy Williams spinning past Hooiveld in the area and flashing a low ball across the face, but Jose Fonte was on hand to clear.
Sam McQueen, arguably the star of Saints’ pre-season trip to the Netherlands and Belgium last week, picked up an injury towards the end of the half and was replaced by Emmanuel Mayuka at the break.
Paulo Gazzaniga was also introduced, with Kelvin Davis being withdrawn.
Saints finally grabbed the lead in the 51st minute, as James Ward-Prowse’s corner drifted to the far post and was poked home by Hooiveld.
Ward-Prowse went close to doubling the lead moments later, but his glancing header from Mayuka’s right-wing cross went over.
Saints made their final nine substitutions all in the 62nd minute, with every remaining starter being withdrawn.
The team saw out the game without much trouble, and they will head to Bournemouth on Friday for their next test.