South Korea's Ji Dong-Won struck in injury time as Sunderland dramatically beat Premier League leaders Manchester City 1-0 at the Stadium of Light here on Sunday.
The result left City ahead of second-placed Manchester United on goal difference alone after they failed to make the most of their local rivals' shock 3-2 defeat by relegation-threatened Blackburn at Old Trafford on Saturday.
There were barely 10 seconds left of added on time when Ji, on as a substitute, was played in by Stephane Sessegnon and beat England goalkeeper Joe Hart from close range, although replays suggested the goalscorer was offside.
Victory lifted Sunderland to 13th place, six points clear of the relegation zone.
City substitute Micah Richards nearly won the match for the visitors with two minutes left when he saw a header come back off the crossbar.
In the first half, City striker Edin Dzeko was denied by Simon Mignolet and the woodwork.
Dzeko's 32nd minute shot was blocked by the keeper and three minutes later the forward clipped the bar while Samir Nasri's effort was cleared off the line by Craig Gardner.
But Sunderland could have been ahead early in the game when striker Nicklas Bendtner was left one-on-one with Hart only for the keeper to come out on top.
And one of the best chances of the second half fell to the Black Cats when Sessegnon outpaced the City defence only to screw his shot wide with just Hart to beat.
In the day's other Premier League match, Victor Anichebe came off the bench to score the only goal of the game in Everton's 1-0 win away to West Brom, the Nigeria striker on target three minutes from time.
Victory for visitors Everton saw them climb to ninth place in the table and dropped West Brom down into 12th spot.
"There were very few chances," said Everton manager David Moyes.
"We were quite brave, we put a couple of forwards on and it paid dividends."
Disappointed Baggies boss Roy Hodgson said: "I don't think we played very well to be honest.
"Everton didn't have to do too much to keep us out so 0-0 would have been a satisfactory result."