Keane quits Sunderland after 100 games

(CNN) -- Roy Keane has resigned after two years in charge of Sunderland, the Premier League club announced on Thursday.

Chairman Niall Quinn told a news conference that he had tried to persuade his former Ireland team-mate to stay, at least for the next three games, but Keane insisted it was time for him to depart.

"Roy Keane isn't resigning because we have a bad team," Quinn said.

"Roy Keane is resigning because he feels we have a good team he can't take forward."

Sunderland have dropped into the relegation zone with 15 points from 15 games and were thumped 4-1 by Bolton on Saturday.

The 37-year-old, who would have been out of contract in the summer, admitted after the defeat that he was not sure he was the best man to arrest their slide.

"I ask myself every day if I'm the right man for Sunderland," he told Press Association after the drubbing. "I asked myself this morning, and I said I was. Sunday morning, if the answer's no, we'll have to look at it."

Recent events are a far cry from the euphoria which greeted Keane on his arrival at the Black Cats in August 2006 with the club in the relegation zone in the second flight of English football.

A remarkable reversal of fortunes saw Sunderland promoted as champions in Keane's first season in charge and they retained their Premier League status for the current season by finishing 15th.

But despite sending an estimated £70 million ($103.80 million) on revamping the squad, success has eluded Sunderland this season, losing six of their last seven games.

Big-money arrivals have included striker Kenwyne Jones, midfielder Kieran Richardson, defender Anton Ferdinand and a club-record £9 millon ($13.35m) on goalkeeper Craig Gordon.

Reports also suggested his relationship with Quinn had become strained, but in a statement on the club's Web site Keane gave no hint of a rift.

"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," he said.

Keane has a history of walkouts, leaving the Ireland camp at the 2002 World Cup finals following a furious row with the coaching staff.

He left United three years later after falling out with manager Sir Alex Ferguson, who was unhappy that he had publicly criticized his teammates' performance and attitude.

First-team coach Ricky Sbragia will take over on a caretaker basis and will be assisted by reserve-team coach Neil Bailey and senior player Dwight Yorke for Saturday's game at Manchester United.

Former Newcastle manager Sam Allardyce was installed as the early favorite to take charge at Sunderland.