Four-time Grand Slam singles champion Naomi Osaka retired from her opening match against Kaia Kanepi at the Toronto Open on Tuesday because of a back injury.
The Japanese former world No. 1 and current world No. 39 was trailing 7-6 (7-4), 3-0 when she withdrew, handing 31st-ranked Kanepi of Estonia a walkover entry into the second round at the WTA 1000 tournament, also known as the National Bank Open.
"I felt my back from the start of the match, and despite trying my best to push through it I just wasn't able to today," Osaka said.
"I'd like to pay credit to Kaia for playing well and want to wish her all the best for the rest of the tournament."
Osaka has suffered numerous injuries in 2022 that have forced her off the court. She pulled out of the Italian Open in May and Wimbledon in June, citing an Achilles injury. She also withdrew from the Melbourne Summer Set 1 in January due to an abdominal injury.
Osaka is a two-time Australian Open champion and two-time U.S. Open winner who ranked as world No. 1 for 25 weeks in 2019.