Guly do Prado's late strike denied Bristol Rovers a point and helped Southampton keep hold of the second automatic promotion spot in League One.
In a fiery first half which saw five yellow cards, Rovers' Jo Kuffour scuffed wide and Jonathan Forte missed a close-range header for the hosts.
Rovers keeper Conrad Logan was forced into a double save from Rickie Lambert and Forte saw another chance go wide.
But Do Prado skipped past two defenders and slammed home to seal the win.
The defeat means the visitors stay in 21st place in the table, level on points with Walsall in 20th and having played a game more than Notts County in 22nd.
Southampton manager Nigel Adkins told BBC Radio Solent:
"They came with a game plan and could have scored two in the first half but great credit to the players because we played some exceptional football in the second half.
"Fantastic supporters - they stayed with us and got behind us when we needed it and we kept chipping away and could have scored eight in the second half
"He's [Lee Barnard] gone to hospital for an x-ray but for him to be in as much pain as he was there's obviously something significant going on in there."