MELBOURNE, Australia -- Simona Halep and Angelique Kerber have held Grand Slam trophies aloft, and so have learned to keep their heads down when clusters of highly ranked players start losing in the first week of majors.
Wimbledon champion Halep and Kerber, who won her breakthrough major in Australia in 2016 and has added two Grand Slam titles since, navigated a chaotic third round at the Australian Open to reach the second week.
Second-seeded Karolina Pliskova, a semifinalist here last year, No. 5 Elina Svitolina and No. 6 Belinda Bencic, a semifinalist at last year's US Open, had straight-sets losses on Saturday, the day after 23-time major winner Serena Williams and defending champion Naomi Osaka exited in third-round upsets.
"Not at all. I'm not focusing on other players -- just focusing on myself," Halep said after her 6-1, 6-4 win over Yulia Putintseva at Rod Laver Arena, the match after Pliskova lost 7-6 (4), 7-6 (3) to 30th-seeded Anastasia Pavlyuchenkova. "It doesn't matter who is winning, who is losing, I just have to do my job when I step onto court."
Kerber had a 6-2, 6-7 (4), 6-3 victory over Camila Giorgi. In a later news conference, she almost laughed when asked if nervousness was contagious in the locker room when the top players start exiting.
"Every match starts from zero -- doesn't matter who against you play," she said. "You have sometimes a little bit bad days, good days. So it's more about caring yourself, working on your strengths and going for it. So it's nothing about looking around."
The left-handed Kerber next faces Pavlyuchenkova, who was a junior champion here 12 years ago when she beat Caroline Wozniacki in the final. They're playing for a spot in the quarterfinals, a stage Pavlyuchenkova has reached five times but never surpassed at the majors.
She said she hasn't been patient enough in the past but is putting more value on each match now. She'd taken only one set off Pliskova in six previous losses but decided to target one of the best serves in the women's game at Rod Laver -- and it worked.
Having a bunch of top players missing from the second week doesn't come into her thinking either.
"I don't focus so much on names anymore. I've been on the tour for a while," she said when asked about the absence of Williams and Osaka, among others. "Those are really big names and great players, but it's tennis. Nowadays, as you can see, surprises happen. I just try not to lose myself and be in the present, do what I have to. I have the next match to play Angelique -- why should I care about all the other names?"
Muguruza, who won the French Open in 2016 and Wimbledon the following year, took the first set in 23 minutes and conceded just 12 points in seven games.
"The first day I didn't feel well at all, but I never throw in the towel," she said. "I'm in the fourth round because of a big fight."
Against Svitolina, a quarterfinalist at the last two Australian Open tournaments and a semifinalist last year at Wimbledon and the US Open, Muguruza was dominant.
"Everything went quickly my way -- yeah, I'll take it," she said. "I played a very good match. I managed to probably disturb her and take the match to my side."
Bertens compiled a 35-19 edge in winners and her serve was broken only once.
The best showing for Bertens at any Grand Slam tournament was a run to the semifinals of the French Open in 2016.
Bertens is the first Dutch woman to reach the round of 16 at the Australian Open since Brenda Schultz-McCarthy in 1996.
Next for Bertens is a match against the unseeded Muguruza.
Williams, who has won seven Australian titles among her 23 majors, 2018 champion Wozniacki and defending champion Osaka all lost on Friday. Wozniacki went immediately into retirement, as she had planned, but Williams vowed to continue her pursuit of Margaret Court's all-time record of 24 majors after her loss to Wang Qiang, a player she'd beaten in 44 minutes at last year's US Open. Osaka, who won back-to-back majors at the 2018 US Open and last year here in Australia, lost to 15-year-old Coco Gauff.
Bencic, a semifinalist at the US Open last September, was rolled 6-0, 6-1 in 49 minutes by 28th-seeded Anett Kontaveit, who will next play Iga Swiatek, the No. 59-ranked player from Poland who took out 19th-seeded Donna Vekic 7-5, 6-3.
Bellis underwent four operations on her right arm and her ranking dropped to 600 in the time between her trip Down Under in 2018 and her return to Melbourne Park. The 20-year-old American was told last year that there was a chance she would never play again.
But she took her place in the main draw on a protected ranking and then upset 20th-seeded Karolina Muchova in straight sets in the second round.
It ended in a 6-1, 6-7 (5), 6-0 loss to Mertens, a semifinalist in Australia in 2018 who had dropped only five games in her two previous rounds.
The Associated Press contributed to this report.