Sunderland have sacked Martin O'Neill following the club's 1-0 defeat to Manchester United on Saturday, a result which left the Black Cats just one point clear of the relegation zone and extended their winless run in the Premier League to eight games.
O'Neill, who took over at the Stadium of Light in December 2011, has been dismissed with immediate effect, with the club confirming that news on his successor will follow.
"The club has parted company with manager Martin O'Neill," a statement on the club's official website read. "Sunderland AFC has announced that it has parted company with manager Martin O’Neill this evening.
"The club would like to place on record its thanks to Martin and wishes him well for the future.
"An announcement will be made in the coming days regarding a successor."
Sunderland will now be preparing for their imminent fixtures without O'Neill as they face Chelsea, Newcastle, Everton and Aston Villa in the coming month, before concluding the season with games against Stoke, Southampton and Tottenham.