Sunderland were denied a precious away win after Virgil van Dijk's stoppage-time strike gave 10-man Southampton a 1-1 draw at St Mary's on Saturday.
The visitors had appeared on course for a crucial three points in their bid to avoid relegation after substitute Jermain Defoe opened the scoring five minutes from time.
However, the Saints - who were reduced to 10 men when captain Jose Fonte was sent off after 79 minutes - drew level through Van Dijk with virtually the last kick of the match.
The point does, though, see Sunderland move a point clear of both Norwich City and Newcastle in the relegation zone, while Southampton move up to eighth in the table.
Ronald Koeman opted to shake things up after Southampton had lost their last two Premier League encounters, with the Dutchman making five changes from their midweek loss at Bournemouth.
The home team were without injured strikers Charlie Austin (hamstring) and Shane Long (knee), with Graziano Pelle recalled to lead the line as the frontman looked to end a goal drought stretching back 12 games to November.
Sam Allardyce, meanwhile, was without captain John O'Shea, with the influential centre-back only fit enough to take his place on the substitutes' bench after failing to recover completely from the calf problem he sustained against Crystal Palace on Tuesday.
However, Allardyce also sprung a surprise by leaving Defoe on the bench as Fabio Borini - who scored the Black Cats' vital late equaliser against Palace - coming in to start up front in his place.
The Sunderland boss had targeted five wins from the final 10 league fixtures of the season for his team to stay up, and judging by the Saints' lacklustre start to proceedings on the south coast, he would have been earmaking this match as one of those.
The visitors enjoyed plenty of possession in the early stages, without ever testing Fraser Forster in Southampton's goal, as recent new signing Jan Kirchhoff took control of the midfield battle.
But it was Southampton who created the first real chance of the game after 26 minutes when a lovely cushioned header back by Pelle set up Dusan Tadic for a shot on goal, only for Vito Mannone to deny the Serb with a brilliant reaction save.
Sunderland also went close before the break as first winger Wahbi Khazri almost caught Forster out with an inswinging free-kick from the left-hand touchline that forced the goalkeeper to turn the ball on to his own bar.
Jack Rodwell should have scored as well after a penetrative run down the left by Patrick van Aanholt, however, the midfielder miscued badly from 10 yards after being picked out perfectly by the Dutchman.
Meanwhile, the Saints had strong appeals for a penalty waved away by referee Neil Swarbrick just before the break after a handball by DeAndre Yedlin.
In the second period, though, it was the visitors who started to look the more dangerous of the two teams.
Sunderland, who brought on Defoe just before the hour-mark, almost broke the deadlock when Borini's well-struck volley from outside the area beat Forster, but flew just over the bar.
And the turning point of the contest appeared to be the sending-off of Fonte 11 minutes from time after the centre-back pulled back Borini on the edge of the box as the Italian broke through on goal.
In fact, it took Sunderland only six minutes to take advantage of their numerical superiority as Defoe toe-poked home Lamine Kone's inviting ball across the six-yard line after Southampton failed to clear their lines.
However, with just a third Premier League away win this season within their grasp, Sunderland conceded in the last minute of stoppage time after Tadic broke clear down the left.
The wide man picked out Van Dijk 12 yards out with an inch-perfect centre, and the Dutchman swept home the equaliser past a helpless Mannone.
Soccer Saturday verdict - Charlie Nicholas
"It will feel like a defeat for Sunderland. When Southampton go down to 10 men and Defoe's nicked it coming off the bench with only five minutes to go plus added time, you really do think 'wrap it up'. It was a killer blow. Sam was looking at his watch, trying to push his team up and you thought he was going to get the win and the clean sheet he was craving.
"To be fair to Southampton, down to 10 men, they came back and got a draw and it's a decent point for them. It was a bright performance from Sunderland, full of energy. They looked a really well-drilled side. Defensively they were good. There are a lot of good things for them. They don't look like a team going down. They don't look that type."
Player ratings
Southampton: Forster (7), Fonte (7), Martina (5), Van Dijk (8), Bertrand (8), Clasie (6), Davis (5), Mane (7), Tadic (8), Romeu (7), Pelle (7)
Used subs: Yoshida (6), Ward-Prowse (6), Juanmi (7)
Sunderland: Mannone (8), Van Aanholt (8), Kaboul (7), Kone (6), Yedlin (7), Rodwell 97), N'Doye (6), M'Vila (6), Khazri (7), Kirchhoff (9), Borini (8)
Used subs: O'Shea (6), Larsson (6), Defoe (8)
Man of the match: Jan Kirchhoff