Naomi Osaka moved into the fourth round at the Miami Open without taking the court on Saturday, getting a walkover victory as Karolina Muchova withdrew.
The former world number one claimed straights sets victories coming into Saturday and had her run eased even further, with Muchova citing abdominal injury after almost five hours on court in her opening two matches.
Muchova has been sidelined due to the injury for the last seven months, missing the US Open in 2021 as well as the Australian Open this year.
"I'm sad that I cannot put up a battle against Naomi today," Muchova tweeted. "After a long break from tennis, two tough matches in [a] row have been a lot for my body and I need longer to recover."
While Lucia Bronzetti also won in a walkover, Osaka will face Alison Riske, who defeated fellow unseeded American Ann Li 6-2, 3-6, 6-3.
In her third match since losing to Ash Barty in the Australian Open final, Danielle Collins defeated Vera Zvonareva 6-1, 6-4 in 78 minutes.
The American world number 11 has had to deal with numerous niggling injuries this season, including a viral illness that left her with significant neck pain.
"There was obviously an emotional moment for me, the pain I'm dealing with right now with this injury," she said post-match.
"Just trying to work through that, I think is one of the hardest things we go through mentally when we're on court."
Fellow seeds Belinda Bencic and Ons Jabeur also made their way through to the fourth round, defeating Heather Watson and Kaia Kanepi respectively.
Both won with relative comfort, Bencic 6-4, 6-1, and Jabeur only dropping three games in the opening set to triumph 6-3, 6-0.
