Dominic Thiem says he is starting to experience physical problems from playing—and winning—so many matches during the first half of the season.
The ninth-ranked Austrian retired with an injury during his opening match in Toronto, stopping at 4-1 down in the first set against Kevin Anderson. He had played his hometown event, in Kitzbuhel, the week before, falling in the opening round in singles but reaching the doubles final.
"It came two weeks ago, and then it got a little bit better in Kitzbuhel,” he said. “And this week it got a little bit worse again. I will go back home now and check everything about it. We can MRI and then we will see, I think. I hope that it's [not] anything really bad."
He had also been scheduled to play Hamburg the week before, but withdrew with illness.
"Maybe I was practicing a little bit too hard after the sickness," he said. "Because obviously I wanted to play well in Kitzbuhel."
Thiem has played a tour-leading 62 matches this season. Novak Djokovic, by comparison, has played 50.
He admitted that he did not anticipate so much on-court success when he planned his schedule.
“I think a little bit difference is, for sure, that I didn't expect to play that many matches, and that many tournaments, and go that deep in almost every tournament,” he said. “And last year, also, I played a lot of tournaments. But obviously I had a couple of first-round and second-round losses ... Yeah, I will have to get used to [playing] that many matches.
"...Yeah, my coach didn't expect that I'd do that well. Myself, for sure, I didn't expect to do that well."
The 22-year-old has won four titles this season. He reached the semifinals of the French Open, which propelled him into the Top 10.