Roy Hodgson was left dejected by Crystal Palace's performance in Tuesday's 3-1 defeat to rival Brighton and Hove Albion, insisting the Eagles cannot use a dubious penalty decision as an excuse.
Referee Kevin Friend awarded Brighton a controversial 24th-minute spot-kick when he deemed that James McArthur had fouled Jose Izquierdo despite winning the ball, with Glenn Murray slotting home.
Shane Duffy's red card handed Palace hope, but a goal from Leon Balogun and then a solo effort from fellow substitute Florin Andone put Brighton out of sight before the interval.
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Luka Milivojevic converted a spot-kick late on, but Hodgson conceded there were no positives to take from an abject display.
"Who knows [if it was a penalty]? We had to adjust it and we didn't," said the former England manager.
"In every game there are so-called injustices and things that do or do not happen.
"It is a fact of life. You have to deal with it. We have to pick ourselves up and we go home knowing it was not the performance, or result we wanted, and learn lessons, so there are no good feelings and nothing positive I can say or feel.
"Things happen. There's no point letting a penalty disturb what you are trying to do.
"You have to make certain that you don’t compound it by conceding two more goals.
"Could things have been different? You can point to that in every game. The second and third goals we can take responsibility for."
Brighton's victory takes them up into 10th, nine points above Palace, who sit 15th, and Chris Hughton was delighted with the resilience his side showed after Duffy's dismissal.
"What you have to do, as soon as it [the red card] happens, is not think about it, but think about what happens then," said Hughton.
"Shane will have to learn from it. He is an experienced player and he should know better.
"It was one of the most special wins not because of the rivalry, but the instances in the game, and probably for what we have learned, going down to 10 men.
"We have learnt from that. They are a gifted side and if they had got a goal earlier, they could have built up a head of steam."