Christian Benteke's injury-time header left Sunderland still waiting for a first Premier League win of the season as Crystal Palace came back from 2-0 down to snatch victory.
Jermain Defoe's double - just his second and third goals at the Stadium of Light since January 2 - had put Black Cats boss David Moyes within 30 minutes of a much-needed victory in front of a crowd of 38,941.
But Patrick van Aanholt's eventful week took a further turn for the worse when he deflected Joe Ledley's 61st-minute shot past keeper Jordan Pickford and was then beaten to the ball by James McArthur as he made it 2-2 before Benteke struck at the death.
With the home side once again misfiring - they were not helped by Steven Pienaar's enforced departure through injury with only 15 minutes gone - the visitors enjoyed the better of the first half, although without converting the pressure into genuine chances.
Benteke headed straight at Pickford and then volleyed wide after controlling a corner on his chest after defender Lamine Kone had hacked Yohan Cabaye's cross over his own crossbar amid an early flurry.
The Palace frontman then stabbed a 25th-minute Jason Puncheon cross over at the near post and then called upon Pickford from a tight angle four minutes later after Andros Townsend had blazed across the face of goal.
Sunderland had created little aside from a clever Defoe flick from a Van Aanholt cross which was deflected just wide of Steve Mandanda's far post, but it was they who took the lead with six minutes of the half remaining, thanks in large part to an horrendous error by midfielder Ledley.
Mandanda spotted the Wales international in space as he looked to play out from the back, but by the time the ball arrived at his feet, red and white shirts surrounded him and as he attempted a return pass, he only succeeded in setting up Defoe to score.
Townsend went just wide with a 30-yard free-kick in stoppage time as Palace looked for a way back, and they might have been level within 10 minutes of the restart when Puncheon got on the end of a pacy counter-attack only to she his shot beaten away by Pickford.
Mandanda came to Palace's rescue on the hour when he parried Defoe's shot after Javier Manquillo's determined run, but the respite was brief and when Watmore crossed from the left, the striker was on hand to smash the loose ball into the net.
However, the visitors were back into within seconds as Van Aanholt's efforts to block Ledley's shot only resulted in him diverting the ball into his own net, and they were level 16 minutes later when substitute Zeki Fryers crossed from the left for McArthur to get ahead of Van Aanholt and head the Eagles level.
But there was worse to come for the home side deep into injury time when Benteke rose to power a header past Pickford from substitute Lee Chung-yong's free-kick and secure a third successive league win for Palace.