Patrick van Aanholt has criticised the training methods of Sunderland boss David Moyes, claiming he had lost his love for the game during the start of the Scots' tenure.
Netherlands international Van Aanholt left Sunderland in January, joining former manager Sam Allardyce at fellow relegation candidates Crystal Palace.
Palace sit four points clear of the drop zone with nine games remaining in their Premier League campaign, while Sunderland are planted to the foot of the table, and Van Aanholt has no regrets about leaving the club.
"I did not enjoy David Moyes' training sessions," Van Aanholt, who is currently out with an ankle injury, said.
"Eventually I lost my love for the game and went into the dressing-room feeling annoyed every day.
"When Sunderland turned down an offer for me from Crystal Palace I went to see Moyes in his office three or four times.
"I was angry. I told him: 'Accept Palace's bid and just let me leave – it is the best thing for all concerned.'
"But he said that he wanted to keep hold of me."
Sunderland slipped further away from safety with a 2-0 defeat to champions Leicester City on Tuesday, piling more pressure on Moyes, who has come under question for remarks made to a reporter following the Black Cats' defeat to Watford.