Former world number one Angelique Kerber survived as three of the top five seeds were bundled out of the Dubai Tennis Championships on Tuesday.
The top seed and winner of two Grand Slams in 2016 dispatched fellow German Mona Bartel 6-4, 6-3 in a second-round match.
World number two Kerber is battling to recover the WTA top ranking she claimed last September when winning the US Open, only to see Serena Williams reclaim it with victory at last month’s Australian Open.
“I’m happy about my performance, I was trying to play my game and focus on every point, I felt strong,” Kerber said.
The German next plays Puerto Rico’s Monica Puig, whom she lost to in the Rio Olympic gold medal match last August.
“That match will be completely different,” Kerber said. “I will try to do my best against her.”
Puig ousted 15th seed Caroline Garcia of France 6-1, 4-6, 6-2.
US Open finalist Karolina Pliskova, last week’s Doha winner and the second seed, was dumped out in straight sets by France’s Kristina Mladenovic 6-2, 6-
Number three seed Dominika Cibulkova fell victim to Ekaterina Makarova 6-2, 4-6, 6-2, having also lost to the Russian in the Melbourne third round.
“It was a tough match again against Domi,” said Makarova. “I started really good with aggressive tennis.
“Beating her at the (Australian) Open helped a lot, I was believing more and I knew what to do, how to play, where to go.”
Roland Garros champion and fifth seed Garbine Muguruza lasted less than 30 minutes on court, retiring at 1-4 in the first set with a foot injury in her second round match against Kateryna Bondarenko of Ukraine.
The physio called it an ankle problem while Muguruza insisted it was an Achilles tendon worry left over from last week in Doha.
“It’s not (the) ankle, that’s ridiculous. The doctor said maybe it’s just inflammation. I have to do an MRI,” Muguruza said.
“I don’t think it’s something big, but it’s very irritated and it’s really bothering me every time I have to run on the court.
“Every time you walk, to kind of have a pain there. It’s kind of (a) new one, honestly.”
Fourth seed Agnieszka Radwanska, the 2012 tournament winner, beat Belgian Elise Mertens 6-3, 6-2 to progress to the third round to help save some dignity for top five seeds.
Elena Vesnina, seeded eight, beat Misaki Doi of Japan 6-2, 7-5 while tenth seed Caroline Wozniacki stopped Swiss Viktorija Golubic 6-4, 6-2 and Ana Konjuh eliminated Australian 12th seed Samantha Stosur 6-4, 6-3.