Harry Redknapp has resigned as manager of QPR just days before he was due to face his former side Saints at Loftus Road, claiming knee replacement surgery would dent the club's Premier League survival fight.

Rangers chairman Tony Fernandes accepted the former Tottenham boss' resignation just a day after tweeting there would be "no more cheque book" as the transfer window closed on Monday.

Redknapp had been under intense pressure for months with QPR languishing in a relegation dogfight, fending off what he claimed was a club insider trying to undermine his position.

Redknapp was Saints boss from 2004-05, having joined from arch rivals Portsmouth. After failing to save the club from relegation he left during the following season to rejoin Pompey.

He had been preparing his side to take on Ronald Koeman's side on Saturday.

Redknapp continuously claimed to have the backing of chairman Fernandes despite being rumoured to be one game from the sack on three separate occasions this season.

Head of football operations Les Ferdinand has taken temporary charge while QPR seek a new manager.

"Sadly I need immediate surgery on my knee which is going to stop me from doing my job in the coming weeks," said Redknapp in a QPR statement.

"It means I won't be able to be out on the training pitch every day, and if I can't give 100 per cent I feel it's better for someone else to take over the reins.

"My relationship with Tony Fernandes has been one of the highlights of my footballing career and I wish the club every success. I am confident they will survive in the Premier League this year.

"I have had such a fantastic time at QPR. I would like to thank the Board, the players and all my staff, and especially the supporters who have been absolutely fantastic to me since I arrived at the club for their tremendous support."

Redknapp had continuously claimed he needed to add a host of January reinforcements to his squad in his bid to help QPR avoid the drop.

Chairman Fernandes seemed to go against the grain with a tweet on Monday's final day of the transfer window however.

The QPR boss tweeted: "No more cheque book. We have good players. Bought all the players manager asked for in summer. Our players not mercenaries. Good guys."

And while Redknapp's imminent surgery will certainly put him out of commission for some time, there was clear strain behind the scenes between manager and board at Loftus Road.

Fernandes still wished Redknapp well in accepting the former West Ham manager's resignation however.

"I would like to take this opportunity to thank Harry for everything he has done for QPR during his time in charge," said Fernandes in QPR's statement.

"We part on good terms and I would personally like to wish him all the best for the future."