London - Sunderland on Saturday sacked manager Martin O'Neill, just hours after a 1-0 defeat to Premier League leaders Manchester United pushed them closer to the relegation trapdoor.
"Sunderland AFC has announced that it has parted company with manager Martin O'Neill this evening," said a club statement.
"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."
The 61-year-old Northern Irishman was in charge at the Stadium of Light for just 16 months having succeeded Steve Bruce in December 2011.
But Saturday's home loss to United left Sunderland just two places and only one point above the relegation zone.
Sunderland have now gone eight games without a win, picking up just two points in the process.
"There is a determination among the players that we can do it. And I'm as buoyant as I've always been," said O'Neill in the immediate aftermath of the loss.
"Overall, I'm pleased with the performance and I think it bodes well. But there's always a danger that you're going to struggle for confidence and self-belief when you haven't won a long time."
His record at the club was 21 wins, 20 draws and 25 defeats in his 66 matches in charge, having taken the club to 13th place in the Premier League in his first season.
O'Neill becomes the fifth top-flight manager to lose his job this season following the sackings of Roberto Di Matteo at Chelsea, Mark Hughes at Queens Park Rangers, Nigel Adkins from Southampton and Reading's Brian McDermott.
Bookmakers quickly made Di Matteo the favourite to take over with Hughes the second-favourite.
O'Neill's sacking, with just seven games remaining in the Premier League season, left observers stunned.
"Surprised Martin O'Neill has been sacked despite their recent run of results. Starting to get tight at the bottom after Wigan's win today," tweeted former England striker Michael Owen.
O'Neill spent the bulk of his playing career at Nottingham Forest, where he won a European Cup winner's medal in 1980.
As a coach, he managed Wycombe Wanderers, Norwich, Leicester, Celtic and Aston Villa before switching to Sunderland.