Burnley manager Sean Dyche praised the strength of his squad after his side secured another away win this season.
With their only effort on target, an 80th minute header from substitute Sam Vokes was enough for the Clarets to leave St Mary's with all three points.
Speaking post-match to Sky Sports, Dyche said: "The depth of the squad and belief was evident.
"The two lads coming on up front in Barnsey and Vokes changed the game. They were terrific in turning the game."
In a rather forgettable affair at St Mary's Stadium, Dyche put on another away day clinic as Burnley picked up their third win on the road this season, in a week that has seen the Burnley manager nominated for the Manager of the Month award for October.
The victory came thanks to a header from substitute Sam Vokes, and Dyche was satisfied with the tactics he employed against Southampton.
He continued, stating: "When you try and plan a game out as you hope it will go then that is as close as we've been to making it work in our favour."
It is a win that moves Burnley up to 7th in the Premier League, level on points with 6th placed Liverpool in what has been a remarkable start to the season for the Clarets.
Burnley return to domestic action in two weeks time due to the international break, when Dyche's men host Swansea at Turf Moor.