The 22-year-old Spaniard lost to top-ranked Jannik Sinner in the Wimbledon final earlier this month in a bid for his third consecutive crown in the grass-court classic.
“I’m really sad to have to miss the National Bank Open in Toronto,” Alcaraz said in a statement.
“I tried my best to be ready for the tournament as it’s one I really enjoy playing, but it comes just too soon for me as I recover after Wimbledon. I wish the event well and look forward to being back on the Canadian courts next year,” he added.
Alcaraz had his best Canada run in 2023, falling to American Tommy Paul in the quarter-finals.
“It’s disappointing to lose a player of Carlos’ quality, as we know our fans were looking forward to watching him,” tournament director Karl Hale said.
“Although he has been on the scene for a while, he’s still at the beginning of his career and there will be plenty of opportunities for Canadians to see him again in the future,” he added.
American Sebastian Korda, the world number 33 struggling with a leg injury, and Poland’s 38th-ranked Hubert Hurkacz, fighting a knee injury, have also withdrawn. (AFP)