Match ends, Southampton 1, Sunderland 1.
Virgil van Dijk snatched a stoppage-time equaliser for 10-man Southampton to deny struggling Sunderland an important victory at St Mary's.
After Saints' Jose Fonte was sent off for hauling down Fabio Borini when the Italian was through on goal, Jermain Defoe put the visitors ahead.
Substitute Defoe finished after good work from Lamine Kone.
Sunderland packed their defence, but Van Dijk still found space in the area to fire in from 12 yards out.
With the bottom three all losing, a win would have taken Sam Allardyce's side three points clear of the relegation zone.
For Southampton, the two dropped home points represent a setback to their hopes of pushing for a place in the Europa League.
Sunderland improve position
Despite the disappointment of conceding so late in the match, Sunderland opened a gap over the bottom three, albeit only one point.
Defeats for Newcastle United, Norwich City and Aston Villa will be some comfort for the travelling supporters, who were just seconds away from witnessing a first clean sheet in 15 Premier League games.
Three points would have been a big lift for the Black Cats, but one could still prove crucial.
Sunderland's next match - in two weeks' time - is a potentially pivotal Tyne-Wear derby against fellow strugglers Newcastle.
Late flurry of drama
The game lacked quality in the final third for the most part, but the final 10 minutes were certainly action-packed.
Once referee Neil Swarbrick decided Saints skipper Fonte had fouled Borini, the 80th-minute dismissal was inevitable.
It boosted Sunderland's hopes of only a third away win of the season, and they took the lead when Defoe scored from eight yards, his 14th goal of the season.
But Southampton were not finished, and Dutch defender Van Dijk hit a sweet left-foot equaliser to snatch a point for his side.
Sunderland should have cleaned up
Few people love clean sheets more than Allardyce, and he must have been relishing the prospect of a first shutout since their 2-0 home win over Stoke on 28 November.
It was a much-improved performance from Sunderland, who were beaten 8-0 here last season, with American DeAndre Yedlin playing a starring role at the back and keeper Vito Mannone pulling off some excellent saves.
Republic of Ireland veteran John O'Shea had come on to give the visitors a fifth defender, but Van Dijk still found the space to fire in the stoppage-time leveller.
That, admitted the Sunderland boss, was a "massive" and costly mistake.
Man of the match - DeAndre Yedlin (Sunderland)
What they said
Sunderland boss Sam Allardyce: "The dejection amongst us all is clear. It was so important to see this game out. We know how important three points would have been.
"If we'd have got the win, we'd have had a gap for next weekend when we're not playing. We dropped a massive clanger in those last few seconds. With the amount of people we had in that box, it's baffling.
"We didn't have the composure to keep the ball, play out and see the game out properly. We paid a very heavy price."
Southampton manager Ronald Koeman: "For 85 minutes, we were not at the level I expect of Southampton. I think we lack confidence at the moment. They made it very difficult with their defensive organisation.
"We played better football with one player less on the pitch.
"The red card was a one-on-one situation. If it's a foul, then it's a red card. You have to accept that."
The stats you need to know
- Defoe scored his 23rd Premier League goal as a substitute; more than any other player.
- Southampton received their fifth red card of the season in the Premier League, more than any other team.
- Jose Fonte was shown his first red card in the Premier League in what was his 129th appearance in the competition.
- Sunderland have gone 15 games without a clean sheet, the longest run of any team in the Premier League this season.
Southampton, with just one point from a possible nine, travel to in-form Stoke City on 12 March.
Sunderland do not play next weekend as scheduled opponents Everton are still involved in the FA Cup.
Next up for Allardyce's men is a crucial derby at fellow strugglers Newcastle United on 20 March.
- 6José FonteBooked at 79mins
- 17van DijkBooked at 31mins
- 21BertrandBooked at 8mins
- 4ClasieSubstituted forJuanmiat 65'minutes
- 8DavisSubstituted forWard-Prowseat 65'minutes
- 10ManéSubstituted forYoshidaat 83'minutes
- 2Cédric Soares
- 3van Aanholt
- 27KirchhoffSubstituted forO'Sheaat 90+1'minutes
- 22KhazriBooked at 11minsSubstituted forLarssonat 76'minutes
- 10N'DoyeSubstituted forDefoeat 59'minutes
- Neil Swarbrick
- Shots on Target
Second Half ends, Southampton 1, Sunderland 1.
Goal! Southampton 1, Sunderland 1. Virgil van Dijk (Southampton) left footed shot from the centre of the box to the bottom left corner. Assisted by Dusan Tadic.
Attempt blocked. James Ward-Prowse (Southampton) right footed shot from outside the box is blocked.
Corner, Southampton. Conceded by Yann M'Vila.
Substitution, Sunderland. John O'Shea replaces Jan Kirchhoff.
Corner, Southampton. Conceded by Vito Mannone.
Attempt saved. Cuco Martina (Southampton) right footed shot from the right side of the box is saved in the top right corner. Assisted by Graziano Pellè.
Attempt blocked. Juanmi (Southampton) left footed shot from the centre of the box is blocked.
Attempt blocked. Dusan Tadic (Southampton) left footed shot from the centre of the box is blocked. Assisted by Graziano Pellè with a headed pass.
Goal! Southampton 0, Sunderland 1. Jermain Defoe (Sunderland) right footed shot from the centre of the box to the top left corner. Assisted by Lamine Koné.
Hand ball by Graziano Pellè (Southampton).
Attempt missed. Sebastian Larsson (Sunderland) left footed shot from the centre of the box is too high. Assisted by Fabio Borini.
Substitution, Southampton. Maya Yoshida replaces Sadio Mané.
Attempt blocked. Jermain Defoe (Sunderland) right footed shot from the left side of the box is blocked. Assisted by Jack Rodwell.
Attempt saved. Patrick van Aanholt (Sunderland) left footed shot from outside the box is saved in the top left corner.
Jose Fonte (Southampton) is shown the red card.
Foul by Jose Fonte (Southampton).
Fabio Borini (Sunderland) wins a free kick in the attacking half.
Attempt blocked. Graziano Pellè (Southampton) right footed shot from outside the box is blocked. Assisted by Sadio Mané with a headed pass.