Ji Dong-Won scored a dramatic stoppage-time winner as Sunderland beat Manchester City 1-0 on Sunday to condemn the leaders to only their second Premier League defeat of the season.
The South Korea striker ran on to Stephane Sessegnon's pass and rounded City goalkeeper Joe Hart to tap into an empty net with just four seconds left of the three minutes of injury time.
City remains top on goal difference from Manchester United but will rue not taking advantage of its archrival's shock 3-2 defeat by Blackburn, the division's bottom side, at Old Trafford on Saturday.
Roberto Mancini's side dominated the match at the Stadium of Light, squandering countless chances with striker Edin Dzeko the guilty party on many occasions.
Substitute Micah Richards did find a way past inspired Sunderland goalkeeper Simon Mignolet in the 88th minute but the right back's downward header struck the bar and was cleared to safety.
More galling for City was the fact that video replays suggested Ji was marginally offside when he ran onto Sessegnon's pass.
''We deserved to win this game. It's incredible. This is football,'' Mancini said.
''We missed a big opportunity because we had a chance to go three points (ahead of) Manchester United. We are probably in an unlucky moment because we missed all these chances to score.''
After starting the season in sensational goalscoring form, averaging nearly four goals a game at one stage, City has now failed to score in its last two matches. This defeat came six days after a 0-0 draw at West Bromwich Albion.
It has now won only two of its last five matches, giving United and Tottenham - which is six points behind in third with a game in hand - renewed hope in the title race. City faces Liverpool at home on Tuesday, in the second of five matches over a 16-day span.
The victory lifted Sunderland three places to 13th and maintained the feelgood factor at the club following the arrival of Martin O'Neill as manager on Dec. 5.
Sunderland has won three of his five games in charge.
''We knew we had to be together as a team and we showed great character to come through,'' Sunderland captain Lee Cattermole said.
