Jannik Sinner, Novak Djokovic and Jack Draper have all withdrawn from the Canadian Open in Toronto, citing minor injuries.
The ATP Masters 1000 event begins on July 26 and runs to August 7, with the women's draw running on the same dates in Montreal.
The men's tournament will now take place without three big stars, though, with world number one Sinner, 24-time grand slam champion Djokovic and world number five Draper withdrawing.
Sinner, whose first ATP Masters 1000 title came in Toronto two years ago, overcame Carlos Alcaraz to win Wimbledon for the first time last week.
The Italian hurt his right elbow when falling awkwardly in the fourth round at the All England Club, going two sets down to Grigor Dimitrov before the Bulgarian was forced to retire due to injury.
Sinner was due to be the top seed in Toronto, but in order to prioritise the defence of his US Open crown in late August and early September, he will now skip the event.
"Winning that title in Toronto two years ago was the start of a really special moment for me, but after speaking with my team, I have to recover," Sinner said.
Sinner overcame Djokovic in the semi-finals at Wimbledon, and the 38-year-old has also opted to skip the Canadian Open after struggling with a groin problem in the later rounds of his run in London.
Djokovic is a four-time champion at the Canadian Open, winning his most recent title without dropping a set in 2016, when he defeated Kei Nishikori in the final.
The Serbian previously won the event in 2007, 2011 and 2012, beating Roger Federer, Mardy Fish and Richard Gasquet in those finals.
Djokovic was due to be seeded sixth, with Draper fourth. However, the British number one is also out after sustaining a left arm injury.
Draper will also miss the Cincinnati Masters, meaning he will not play a hard-court event before the US Open begins on August 24.
With the trio all absent, Wimbledon runner-up Alcaraz will be the top seed, with Alexander Zverev – the 2017 Canadian Open champion – seeded second.
