Saints finished off their pre-season tour to Holland with a 1-0 win over ten-man FC Groningen on Saturday afternoon.
Charlie Austin's 75th minute header was enough to make sure Claude Puel's men ended their week in the Netherlands with a perfect record, following the victories over PEC Zwolle and FC Twente earlier in the trip.
Puel handed Fraser Forster and Shane Long their first appearances of pre-season, at the Euroborg. Fellow EURO 2016 participants Steven Davis and Ryan Bertrand were not included, however, while Jay Rodriguez was also absent.
It was Groningen that started brightest, with Albert Rusnak cutting onto his right foot on the edge of the area and firing just wide after six minutes, while Jesper Drost shot over shortly afterwards from 18 yards.
Puel was forced into an early change, with Matt Targett picking up a knock in a challenge and needing to be replaced by Sam McQueen.
A series of bookings followed, with Oriol Romeu first carded for a late tackle on Hiariej, before the Groningen man got his own back a few minutes later and duly went into the book.
Hans Hateboer was the next man to be cautioned for the hosts, for a bad challenge on Nathan Redmond, and he was sent off seven minutes before the interval when he hauled down the Saints winger as he raced in behind, with referee Jochem Kamphuis showing him a second yellow.
James Ward-Prowse, who had earlier cleared a header off his own lie from a corner, nearly issued a double punishment, but his wicked free-kick was well tipped over by Sergio Padt in the Groningen goal.
Puel made three changes at the interval, as Pierre-Emile Højbjerg, Jake Hesketh and Austin came on for Maya Yoshida, Dušan Tadić and Long.
Virgil van Dijk, up against his first professional club, attempted the spectacular shortly after the restart, but his long-range drive flew a few yards wide of the post.
Saints made more changes just after the hour mark, with Yan Valery, Sam Gallagher, Lloyd Isgrove and Harrison Reed all coming in, in place of Cuco Martina, Nathan Redmond, James Ward-Prowse and Jordy Clasie.
Reed nearly scored within moments of coming on, but his left-footed strike from 18 yards came back off the bar.
Van Dijk then went close with 20 minutes remaining, firing in a dipping free-kick that Padt had to parry clear, shortly after Jack Stephens had been sent on for Romeu.
Saints did finally make the extra man pay with 15 minutes left on the clock, as Austin rose to meet Jake Hesketh's cross from the left, with his header bouncing in off the far post to give Puel's men the win.
FC Groningen: Sergio Padt (c), Etiënne Reijnen, Jarchinio Antonia, Ruben Jenssen (Mimoun Mahi 68), Albert Rusnak, Jesper Drost (Tim Riksman 80), Tom van Weert (Danny Hoesen 57), Yoëll van Nieff (Roland Baas 85), Hedwiges Maduro, Tom Hiariej (Juninho Bacuna 63), Hans Hateboer.
Unused substitutes: Stefan van der Lei (GK).
Booked: Tom Hiariej, Hans Hateboer.
Sent off: Hans Hateboer.
Southampton: Fraser Forster, Maya Yoshida (Pierre-Emile Højbjerg 46), Jordy Clasie (Harrison Reed 63), Shane Long (Charlie Austin 46), Dušan Tadić (Jake Hesketh 46), Oriol Romeu (Jack Stephens 68), Cuco Martina (Yan Valery 63), James Ward-Prowse (Lloyd Isgrove 63), Virgil van Dijk (c) (Alfie Jones 83), Nathan Redmond (Sam Gallagher 63), Matt Targett (Sam McQueen 6).
Unused substitutes: Harry Lewis (GK).
Booked: Oriol Romeu.
Goal: Charlie Austin (75).
Referee: Jochem Kamphuis.