Disappointed Roy Keane felt his side were punished after spurning a host of great chances against victors Portsmouth.
Sunderland have now recorded three straight defeats in the Premier League and looked to have changed their fortunes when Djibril Cisse scored early on.
However the Frenchman's strike was cancelled out by a Nadir Belhadj effort and the Black Cats were punished in the final minute from a Jermain Defoe penalty.
But Keane tried to remain upbeat and appeared more disappointed than disheartened believing his side were punished for not being clinical enough in front of goal.
"I certainly didn't feel we deserved to lose the game and we had enough chances, particularly in the first half, to maybe be two, three-nil up at half-time," he told Sky Sports.
"Second-half we found it hard going, but one or two minutes left you think you can take your point, but to throw it away like that is hard to take.
"We all know in football when you're one-nil up and you don't take those chances it comes back to haunt you."
Keane had no complaints over El-Hadji Diouf's desperate lunge in the final minute which brought down Glen Johnson for the penalty which was coolly converted by Defoe.
"I really can't fault the players too much there I thought we did enough to at least get a draw.
"But we know the Premiership is so tight and any sort of mistake, like we did with a minute to go, you get punished and that's why you see the Premiership's so tough," Keane said.
With a tough home game against Blackburn on Wednesday in the Carling Cup, Keane hopes it will spur on his side to turn around their mixed fortunes of late.
"We need to react now. It's a busy time coming up for us, it's a big test for everyone, myself, the staff and the players.
"But we lick our wounds and hopefully we'll have one or two games to bounce back and we'll live to fight another day," he added.