Andy Murray has withdrawn from the Rogers Cup in order to give himself more time to heal a troublesome hip injury, while Marin Cilic will also not play in Toronto.
World number one Murray was hampered with the issue before his Wimbledon defence and was clearly affected as he went crashing out in the quarter-finals to Sam Querrey.
Murray had played in Toronto every year from 2006 to 2015 but skipped the event last year to focus on the Rio Olympics and will sit out again in order to rest up.
"I am sad to be missing the tournament in Montreal because I have many great memories from my time in Canada," three-time champion Murray said.
"I am doing everything I can to return as quickly as possible."
Cilic, ranked sixth in the world, enjoyed a memorable run to the final at Wimbledon where he was beaten by the evergreen Roger Federer.
The Croatian suffered an adductor injury at SW19, though, and has opted not to participate, with Cilic perhaps thinking ahead to the US Open, which begins on August 29.
Last month, former world number one Novak Djokovic announced he will be sitting out the remainder of ATP season due to an elbow injury.