Referee Mike Jones was unerring in his decisions to award the Black Cats a spot kick in either half, as well as his dismissal of James Ward-Prowse which paved the way for the game’s second spot kick that confirmed the hosts’ win.
Sunderland started and finished the scoring in the contest with efforts from 12 yards both converted by Jordi Gomez.
In truth, Sunderland looked unlikely to score from open play, and when Sadio Mané equalised within a minute of the hosts’ opener, it seemed there was only going to be one way that Saints would lose, and so it proved as the team with a man light were unable to fight back.
Ahead of kick-off Victor Wanyama returned from a two-game ban to take up a place in the Saints midfield vacated by the injured Morgan Schneiderlin. Shane Long also came into the side, with Dušan Tadić missing after taking a knock during the week.
Saints, in their changed strip of navy shirts and shorts with yellow socks, got the game under way, and the visitors made a positive start too, as Ryan Bertrand flashed a shot wide from the left side of the area with less than two minutes on the watch.
Sunderland showed that they’d be a physical opponent for Saints during the opening exchanges, though the match officials tried to let play run as much as possible.
That was, until the 21st minute when Sunderland were awarded a penalty after Fonte was adjudged to have fouled Mackems striker Danny Graham, who was caught by the skipper’s boot as he tried to follow up on a shot at goal.
Kelvin Davis was beaten by Jordi Gomez’s strike from the spot which found the bottom right corner, to give the hosts a surprise lead.
It was an advantage that was quickly lost though, as Saints equalised 78 seconds later. A long ball forward from Fonte was dropped by goalkeeper Costel Pantilimon who collided with his own defender, Sebastian Coates, and the ball fell kindly to Sadio Mané, who gleefully slotted home just inside the area for his seventh goal of the season.
It was a terrific response from Koeman’s men, who then almost turned the game on its head when Bertrand found Pellè with a cross from the left, and the Italian headed over with a diving effort from close range.
However, it was the hosts who were nearly celebrating when Patrick van Aanholt’s low cross was met by Connor Wickham inside the area, but the striker couldn’t keep his shot down as Saints were given a let off.
Sunderland turned the screw towards the end of the half and went close again when Wickham’s deflected strike from the left side of the area bounced up for Jermain Defoe, whose header was clawed away by Davis, before Fonte got the vital interception to Graham’s follow up to deny a tap-in.
Sebastian Larsson’s well-struck free-kick made Davis work again in stoppage time as Saints started to look vulnerable, but the teams remained level going into half-time.
Filip Djuričić was introduced for Shane Long for the start of the second half in a tactical move, with the Serbian tucking in from the right side to support Ward-Prowse in midfield.
And the substitute almost made an immediate impact as he broke into the area on the right side and flashed a shot wide in the 51st minute.
Sunderland had offered little of note until they were awarded a penalty on 54 minutes after Defoe had gone to ground under a last ditch challenge from Ward-Prowse, with the Saints man shown a straight red card for his foul.
Gomez stepped up to covert from 12 yards again, going the same way as he did for the first penalty to put the hosts back in front.
Lee Cattermole was booked for a poor tackle on Alderweireld, then Wanyama into the book soon after, as tensions were raised further.
Mané was on the receiving end of another challenge from Cattermole which would eventually curtail the Senegalese’s involvement in the game, with the forward replaced by Eljero Elia in Saints’ final change with 20 minutes remaining.
Only one further clear opportunity really came the visitors’ way, with Alderweireld seeing a strong strike saved by Pantilimon from point-blank range. The team’s fourth defeat from the past five away matches then confirmed after four minutes of stoppage time.
Saints’ last win on the road was at QPR in February, and they will look to improve that record with a trip to in-form Leicester City next weekend.
Sunderland team: Costel Pantilimon, Billy Jones, Patrick van Aanholt, John O’Shea (c) (Santiago Vergini 31), Sebastian Coates, Lee Cattermole, Sebastian Larsson (Jack Rodwell 82), Jordi Gomez, Danny Graham, Connor Wickham, Jermain Defoe (Adam Johnson 82)
Unused substitutes: Vito Mannone, Liam Bridcutt, Anthony Reveillere, Will Buckley
Booked: Jones (32), Cattermole (60)
Goals: Gomez (pens) (21) & (54)
Southampton team: Kelvin Davis, Nathaniel Clyne, José Fonte (c), Maya Yoshida, Ryan Bertrand, Victor Wanyama (Steven Davis 66), Toby Alderweireld, James Ward-Prowse, Shane Long (Filip Djuričić 46), Sadio Mané (Eljero Elia 70), Graziano Pellè
Unused substitutes: Paulo Gazzaniga, Florin Gardos, Harrison Reed, Matt Targett
Booked: Wanyama (63), Pellè (90)
Sent off: Ward-Prowse (53)
Goal: Mané (22)