Sunderland "dropped a massive clanger" in their bid to avoid relegation from the Premier League by failing to beat 10-man Southampton at St Mary's on Saturday, according to manager Sam Allardyce.
The Black Cats were within touching distance of what would have been just a third away league victory this season after substitute Jermain Defoe opened the scoring with only five minutes left to play.
However, despite also seeing their opponents reduced to 10 men when Jose Fonte was sent off for a professional foul on Fabio Borini after 79 minutes, Sunderland were still unable to hold on for the win.
And Allardyce said his side had "thrown away two points" by allowing Southampton defender Virgil van Dijk to equalise with virtually the last kick of the game.
"I think that at this moment in time the dejection among all of us is clear in the dressing room; how important it was to see this game out having been 1-0 up with just about 30 seconds left to play and conceding the goal," he said.
"Total dejection in the dressing room knowing we should have taken three points here today, which would have made life so much easier for us in this relegation battle that we are in.
"Because we have thrown two points away, we have heaped a massive amount of pressure on ourselves yet again by not achieving that clean sheet."
Sunderland's draw on the south coast did move them a point clear of Norwich City and Newcastle United - who both lost on Saturday - in the relegation zone with nine matches left this season.
But had the visitors held on, they would have enjoyed a three-point advantage over their relegation rivals, as well as a superior goal difference.
"And having no game next week, because we should have played Everton and they are in the cup, means that had we got the three points today, we would have had a three-point gap to look after next weekend in case anybody put a victory on the board and would actually just catch us up," Allardyce said.
"But then we would have a game in hand on them, which would be a home game against Everton when it came around.
"So we have dropped a massive clanger in those last few seconds in allowing Southampton to score a goal, which really should have been prevented by us, certainly with the amount of people we had back defending our box."
In particular, Allardyce was disappointed with his players for firstly failing to prevent Dusan Tadic's cross and then for not picking up Van Dijk for the Saints' stoppage-time leveller.
"Nobody going to stop the man who got the cross in and there was a man who we elected to let run free in the box, which is baffling to be perfectly honest with you, totally and utterly baffling," he said.
"Then not [having] the composure to keep the ball and just play our way out and get into the opposition's half and in the corners and see the game out properly. And we did not do that and ultimately we paid a very heavy price today."