Andre Agassi has withdrawn from next week's Canadian Open, organisers said on Friday.
Three-times winner of the Masters event and runner-up last year in Montreal, the tournament was to be Agassi's final appearance in Canada before the eight-times grand slam retires at the US Open.
"I regret to inform Toronto that I will not be playing in the Rogers Cup," Agassi said in a statement. "I have many great memories in Canada and wish you continued success. It's a fantastic tournament."
No official reason was given for Agassi's decision to pull out of the event, which begins on Monday.
"He was a finalist last year in Montreal and was not able to compete the following week in Cincinnati," said tournament director Grant Connell. "This year he decided to switch events.
"We are disappointed that he will not be able to play one last time in Toronto but understand his situation."
Nine of the world's top 10 players will be in the Canadian draw, including world number one Roger Federer and French Open champion Rafael Nadal.