PARIS -- Naomi Osaka is grinding her way through the French Open the hard way.
To cling onto her quest for a third consecutive Grand Slam title, the top-ranked Osaka again had to rally from first-set woes to beat former No. 1 Victoria Azarenka 4-6, 7-5, 6-3 Thursday in the second round.
She wasn't the only high seed to get out of trouble on Thursday. Defending champion Simona Halep blew a big lead in the second set and ran into more trouble in the third before holding on to beat 87th-ranked Magda Linette of Poland 6-4, 5-7, 6-3.
Osaka considered herself unfortunate to be drawn against Azarenka and the powerful, accurate tennis produced by the 29-year-old Belarusian playing in her 12th French Open showed why.
Although now ranked No. 43 and without a major title since winning the Australian Open in 2012 and 2013, Azarenka took a 4-0 lead on Court Suzanne Lenglen and kept Osaka under constant pressure.
"I got rolled," Osaka said. "Technically, like, she kind of killed me in the first set, and I just kept trying a way to stay positive."
Broken by a backhand volley at the net from Azarenka in the fifth game of the second set, Osaka seemed to be in deep trouble. But, as she did in beating first-round opponent Anna Karolina Schmiedlova, Osaka again proved her resilience.
"I didn't stop trying at all," Osaka said. "Every point was kind of, like, pedal to the metal.
"I have this mindset that I feel like I can win if it gets down to the wire. Like, if I have to break a person, I feel like I have the ability to do that. So I probably shouldn't wait until the last minute."
The eighth game of the second set was pivotal. After saving two break points, Azarenka doubled-faulted. Osaka leveled at 4-4 and the momentum started to shift. It was the seventh break point Azarenka had faced in the set, and the first she had failed to save.
But Azarenka still saved three set points before Osaka finally leveled the match with a backhand cross-court winner.
The third set was packed with drama, too, with Osaka finally taming Azarenka with her third match point, when her combative opponent hit long.
"Today I kind of felt like a challenger," Osaka said. "Like, I know she went to the semis here before, so obviously she has a lot more experience here. She won Grand Slams and she was No. 1 way before I was. I'm still kind of new at this."
Azarenka, still working her way back into the upper echelons of the game after injuries, a pregnancy and a custody battle over her child, said she would learn from the defeat.
"I know what I need to do better, so it keeps me optimistic, and I do enjoy this. No matter how hard it is, it's my path that I'm going to walk with my head held high," Azarenka said.
Osaka's next opponent, 42nd-ranked Katerina Siniakova, hasn't been past the third round in her 18 previous Grand Slam tournaments.
"She's very powerful. She's very explosive," Azarenka said of Osaka. "Her shots are pretty heavy. She can hit both sides, pretty even. She has a big serve, and she's consistent. ... And proving that she deserves to be where she's at right now."
Meanwhile, Halep looked headed for a relatively straightforward, straight-set victory -- until everything started to fall apart for her after dropping four games in a row in the second set.
After surviving to win the match, Halep said she felt a "little bit sick" and plans to "sleep all day" on Friday.
Against Linette, she was up a set and a break at 5-3 in the second before losing her way. Halep got broken when serving for the match at 5-4 in that set, and again at 5-2 in the third.
She wasted three set points along the way, before converting her fourth when Linette netted a forehand.
In another match, American teenager Amanda Anisimova continued her dominance over 11th-ranked Aryna Sabalenka at Grand Slam events with a 6-4, 6-2 victory in the second round.
The 17-year-old Anisimova, who is ranked No. 51 and is making only her second appearance at Roland Garros, previously beat Sabalenka in the third round of the Australian Open in January.
The Associated Press contributed to this report.