Two of the top three seeds at the Dubai Duty Free Tennis Championships were sent packing on Tuesday.
France's Kristina Mladenovic rolled to an impressive 6-2, 6-4 victory over second-seeded Karolina Pliskova of the Czech Republic, while Russia's Ekaterina Makarova recorded a 6-2, 4-6, 6-2 win over third-seeded Dominika Cibulkova of Slovakia.
In addition, fifth-seeded Garbine Muguruza of Spain was forced to retire due to a left Achilles' tendon injury. She was trailing 4-1 when she withdrew against Kateryna Bondarenko of the Ukraine.
Mladenovic reached the third round behind a strong effort in which she broke Pliskova's serve four times in a 75-minute match.
"I just came on court strong, ready to play for as long as I needed to, fighting out there," Mladenovic said. "I thought I played very aggressively on return. At the beginning, she double faulted a couple of times and it's always weird when we know each other so well.
"I think I was lucky that the first serve percentage wasn't that high from her. It's her biggest weapon, but I definitely took advantage and overall I'm happy about my performance."
Pliskova wasn't so thrilled about her own performance.
"I think I was mentally like there. I was still trying, even in the second set," Pliskova said. "But I was just playing really bad, so there is not much what you can do about it. Like, I still had a chance in the second set, you know, to change this to have 5-4, but yeah, she played some good points."
Meanwhile, Makarova knocked off Cibulkova for the second time this year. She also prevailed in a third-round match at the Australian Open.
She set the tone with her 6-2 win in the opening set. Cibulkova battled back to win the second before Makarova dominated the third set.
"I started really well but I know that Domi is an unbelievable fighter and she's fighting until the end," Makarova said. "The second set was a little up and down and I tried to stay calm into the third set when I was losing 2-0 and it helped me this time, believing I could beat her.
"I was serving really well and, in the important moments, I hit good returns. When I'm staying close to the baseline, I play much more aggressive than when I'm staying back a little bit."
Muguruza decided to call it a day when the Achilles was throbbing during her match against Bondarenko.
She said she was experiencing pain in the same area during last week's Qatar Open. Muguruza said she would be undergoing an MRI exam.
"When I finished in Doha, because of the rain, a lot of people played two matches, including me," Muguruza said. "The second one was very tough, and 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 been carrying this since that day. And here, I have been training but on and off, honestly, because of the pain. Some days it was a little bit better, some days it was a little bit worse. It was just hard for me to serve, especially, and to just move side to side today on the court."
Among the other players to advance to the third round was top-seeded Angelique Kerber, who posted a 6-4, 6-3 win over fellow German Mona Barthel.
Kerber next faces Puerto Rican Monica Puig, who defeated 15th-seeded Caroline Garcia of France 6-1, 4-6, 6-2.
It will be a rematch of the Summer Olympics tennis final when Puig defeated Kerber to win the gold medal.
"I think it'll be a completely new match," Kerber said. "For sure she's a tough player and I know her. She plays really aggressive, I know this from the match in Rio.
"But for me, it's the same like tonight; I will just go out there trying to play my game again. And I will not be thinking too much about the match in Rio -- she played an unbelievable match and she won it. She played from the beginning really one of the best matches I think she played.
In other matches involving seeded players, fourth-seeded Agnieszka Radwanska of Poland won 6-3, 6-2 over Elise Mertens of Belgium; seventh-seeded Elina Svitolina registered a 7-5, 6-1 victory over China's Saisai Zheng; eighth-seeded Russian Elena Vesnina defeated Japan's Misaki Doi 6-2, 7-5, and 10th-seeded Caroline Wozniacki of Denmark defeated Switzerland's Viktorija Golubic 6-4, 6-2.