* O'Neill departs after home defeat by Manchester United
* Former England boss McClaren early favourite to take over
* Announcement on successor in coming days, says club
Sunderland pushed the panic button and sacked manager Martin O'Neill on Saturday after a 1-0 Premier League defeat at home to Manchester United left them facing the prospect of relegation.
Without a win in eight games, Sunderland have plummeted down the table to 16th place, having played a game more than Wigan Athletic and Aston Villa, their two main relegation rivals.
"Sunderland AFC has announced that it has parted company with manager Martin O'Neill this evening," the north-east club said on their website (www.safc.com).
"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."
With only seven games of their league campaign remaining, Sunderland have little time to waste in finding a replacement.
"An announcement will be made in the coming days regarding a successor," the club statement added.
Former England manager Steve McClaren was installed as the early favourite with ex-Swindon Town boss Paolo Di Canio and former Chelsea manager Roberto Di Matteo also in the running.
O'Neill's fate was sealed by the home defeat to runaway league leaders Manchester United, with a Titus Bramble own goal in the first half handing the visitors a seventh successive league victory.
However, it was not the sort of one-sided match or hapless display that has typically felled managers embroiled in relegation scraps.
"It was a battle in the second half and you have to give Sunderland credit as they had a real go at us," United manager Alex Ferguson's said in his post-match verdict.
O'Neill began his coaching career in semi-professional football in 1990 with Wycombe Wanderers, before joining Leicester City in 1995 with whom he won promotion to the Premier League and two League Cup triumphs.
He moved to Celtic in 2000, winning a Scottish domestic treble in his first season before lifting two more league titles and two more Scottish Cups and reaching the 2003 UEFA Cup final.
He spent four years at Aston Villa from 2006 before joining Sunderland in 2011.