DUBAI, United Arab Emirates (AP) — French Open champion Garbine Muguruza retired with a left Achilles injury and U.S. Open finalist Karolina Pliskova was knocked out in the second round at the Dubai Tennis Championships on Tuesday.
The seventh-ranked Muguruza drew the trainer on court when trailing Kateryna Bondarenko of Ukraine 3-0, and quit at 4-1 down.
Muguruza said she started to feel the injury following her second-round loss in Doha last week.
"Because of the rain (in Doha), a lot of people played two matches (in one day), including me," she said. "I remember that as soon as I went, after the match, to my room, I started to have a pain in my left Achilles.
"The next morning was even more painful. I have carried this since that day. And here, I have been training but on and off, honestly, because of the pain. It was just hard for me to serve, especially, and to just move side to side."
Second-seeded Pliskova was upset by Kristina Mladenovic of France 6-2, 6-4.
Pliskova won her second title of the year in Doha last weekend, defeating former No. 1 Caroline Wozniacki in the final.
After a first-round bye in Dubai, she struggled with her serve, double-faulting six times and losing her serve four times to Mladenovic.
"I still had a chance in the second set, but she played some good points," Pliskova said.
Pliskova boasts a 15-2 win-loss record this year. Her only prior defeat was to Mirjana Lucic-Baroni in the Australian Open quarterfinals.
"I don't want to be disappointed about this match, because I won so many matches already this year," Pliskova said. "I'm just happy about it, and this was just one bad tournament, I would say. I'm going to forget about this one, like, really fast."
Earlier, Ekaterina Makarova advanced to the third round by beating third-seeded Dominika Cibulkova 6-2, 4-6, 6-2.
The Russian lost her first three matches against Cibulkova, but Makarova eliminated the Slovak in the third round of the Australian Open.
"I never beat her before (Australia)," Makarova said. "So this match, when I was coming out and ... more believing that I can win, and I knew what to do, how to play, where to go."
Cibulkova took a 2-0 lead in the third set, but Makarova won the last six games.
Also, Olympic champion Monica Puig, and eighth-seeded Elena Vesnina advanced.