Pep Guardiola admitted Manchester City had only themselves to blame as the leaders wasted a chance to wrap up the Premier League title against bitter rivals Manchester United.
City were cruising towards the win they needed to seal the silverware thanks to first half goals from Vincent Kompany and Ilkay Gundogan at Eastlands.
But Guardiola's side crumbled in unexpected fashion in the second half as Paul Pogba's brace and a Chris Smalling strike put City's title champagne on ice for at least another week.
"We were not good enough in the end. Our team tried to create and attack, that is what we have done all season, we tried to produce all of that quality and goals," Guardiola said.
"A special day for United which is a pity. We did absolutely everything in the first half but then for 10-15 minutes we conceded goals.
"United found their game, found their actions, they have spirit. We have to defend a little better in the second half."
After their chastening midweek 3-0 defeat at Liverpool in the Champions League quarter-final first leg, surrendering the lead against United was another bitter blow for City.
They could still be crowned champions next weekend if they win at Tottenham and second placed United lose to struggling West Bromwich Albion.
But for now Guardiola has to focus on restoring his players' morale for the second leg against Liverpool on Tuesday.
"It's a little sad for fans and players, we will try to be in a good mood next Tuesday," he said.
"We will try to pick ourselves up for Liverpool, we are professionals."