Roy Keane has resigned as Sunderland manager following a dreadful run of form that has plunged the club into the Premier League's relegation zone.
Five defeats from their last six league games left the Irishman locked in talks with chairman Niall Quinn and Saturday's 4-1 thrashing at home to Bolton Wanderers caused Keane to question whether he was the right man for the job.
He said in the post-match interview: "I ask myself every single day if I am the right man for Sunderland. I asked myself this morning and I said that I was. Tomorrow morning if the answer's no we will have to look at it."
The former Manchester United and Celtic midfielder used 27 players this season as he struggled to find a winning formula in his first managerial position, but was unable to do so.
Quinn confirmed that Keane's departure was conducted in an amicable manner and thanked the 37-year-old for all his efforts as Sunderland manager.
"Roy deserves huge respect for his contribution and the manner in which he guided the club from the depths of the Championship back to the Premier League," the Sunderland chairman said.
"Roy's decision to stand aside and allow someone else to take charge of the next chapter sums up his desire to always do what is best for the club. Even in his departure he has been more concerned for the welfare of the players and his staff than himself.
"The board has reluctantly accepted his decision and wish him and his family well for the future.''
Keane added: "I would like to thank my staff, players, Niall Quinn and in particular the fans for their support during my time at Sunderland, and I would like to wish the club every success in the future.''
First-team coach Ricky Sbragia will take over on an interim basis, assisted by reserve-team coach Neil Bailey and senior player Dwight Yorke, but has only a few days to prepare for trip to Old Trafford to face Keane's former club Manchester United.
Sunderland were bottom of the Championship when Keane took over in August 2006 and he guided the club to the top of the division, winning promotion in his first season.
He spent over £80 million in less than two seasons in the top flight but summer signings such as Anton Ferdinand, Pascal Chimbonda and El-Hadji Diouf have largely failed to deliver.
His contract was due to expire at the end of the season with talks over a new deal reportedly ongoing.
Former Newcastle United and Bolton manager Sam Allardyce is the bookies' early favourite to become the new manager at the Stadium of light.