Sir Alex Ferguson admitted Paul Scholes had one of his "red-mist moments" when he was sent off in Manchester United's FA Cup semi-final defeat.
Scholes was dismissed for a thigh-high lunge on Pablo Zabaleta as United tried to fight their way back into Saturday's clash with Manchester City at Wembley.
The red card proved costly, with City holding on to win 1-0 to end their arch-rivals' treble bid and reach their first cup final for 30 years.
United boss Ferguson insisted Scholes' sending off "didn't kill the game" because the 10 men piled on the pressure in the closing stages.
But he added: "We've seen over his career Paul has had unbelievable moments - he's one of the greatest players this club has ever had.
"But he has his red-mist moments - he caught the boy on the thigh."
Ferguson blamed today's defeat on the slack defending which led to Yaya Toure's winner, as well as two of the misses of the season from Dimitar Berbatov.
"The first 15 minutes after half-time cost us the game," Ferguson said.
"Slack moments. Edwin (van der Sar) had a bad kick out and Michael Carrick couldn't hold it and it was a goal.
"From then on, they were defending apart from a couple of counter-attacks. It's disappointing as we should've been ahead in the first half as we were the better team.
"The chances that Dimitar missed - there was a great save by the goalkeeper but the second chance, from under the bar, if he'd have scored there, I had a feeling whoever scored first would win the match."
Ferguson challenged his players, who had won their previous seven matches, to bounce back in Tuesday night's Premier League game at Newcastle.
"It's a major game on Tuesday up at Newcastle," he told MUTV. "We're getting recovered to get ready for the game on Tuesday.
"It doesn't matter when you play, you know you've got to recover and get on a winning streak again."