After spending nearly five hours on the court across his opening wins against Lorenzo Sonego and Max Purcell, the Briton was set to face Sinner but he pulled out.
“I have an issue with my abdominal (muscles) so unfortunately I’m not going to be able to play this evening. I’m really sorry,” Murray said, addressing the stadium crowd.
“I feel like I’ve let you down. I’ve rarely been in this situation in my career and I feel terrible,” he added.
It is just Murray’s seventh time conceding a walkover in his long career. A three-time champion at the ATP Masters 1000 in Canada (2009, 2010, 2015), the 36-year-old was especially upset given that this might be his last appearance in Toronto.
He was seeking his first quarterfinal at the event since his 2015 title run, and his first Masters quarter-final since he won the Paris crown in 2016.
“I don’t know, this might be my last time playing here as well. So to finish like this feels rubbish,” Murray said before thanking the Canadian fans for their support over the years. He also took time to sign autographs before leaving the court.
The 36-year-old Murray is up four places to No.36 in the ATP Live Rankings behind his two wins this week — his highest mark since 2018 — and is hopeful for a speedy recovery with Cincinnati and the US Open around the corner.
“I had a very similar issue last year in Stuttgart before Wimbledon, which forced me to miss the Queen’s Club tournament. I was able to play Wimbledon. It took me about 10-12 days before I was feeling good again,” he recalled.
“This is not as bad as that but obviously the danger if you compete and play is you could make it worse. I’ll need to see how it develops over the coming days and hopefully feel better in a few days,” he added.
Courtesy of the walkover, Sinner advanced to face Gael Monfils in Friday’s quarterfinals and moved ahead of Andrey Rublev into fifth in the ATP Live Race To Turin.