MELBOURNE, Australia -- For the first set, Naomi Osaka's rediscovered love of the game meant it was anything but fun for Madison Brengle in the second round of the Australian Open.
The defending champion conceded only four points in the first four games Wednesday and rifled forehand winners seemingly at will as she breezed to 6-0 in a mere 20 minutes.
The second set started with Brengle celebrating a service hold like she'd finished a long-distance race, but gradually the No. 54-ranked American's keep-the-ball-in-play strategy ground down Osaka to a stage where she finally converted a break-point opportunity -- after missing her first nine chances.
That triggered a change in the former No. 1-ranked Osaka, who responded by breaking back immediately and reeling off the last nine points to complete a 6-0, 6-4 victory. She finished with 37 winners and 32 unforced errors.
Osaka will next face Amanda Anisimova, a 20-year-old American who beat Olympic gold medalist Belinda Bencic 6-2, 7-5. The winner of that is likely to face top-ranked Ash Barty in the fourth round.
Osaka won the Australian Open last year, her fourth Grand Slam title, but then withdrew from the French Open and skipped Wimbledon as she took a break for her mental health. She then was ousted early at the U.S. Open.
After a long off-season to reset, she's unbeaten in five matches in Australia this year.
Asked how she rated her form, Osaka said that's not how she's approaching things.
"Honestly I'm trying not to do that," she said in an on-court TV interview. "I'm a bit of a perfectionist. If I compare myself with the past, I'll never be satisfied.
"The goal for me is just to have fun ... (and) I think we're accomplishing that."
Since the draw for the first major of the year was made, a big focus has been on a potential encounter between Osaka and Barty, the 2021 Wimbledon and 2019 French Open champion who is aiming to be the first Australian woman since 1978 to win her home championship.
Barty was front and center when the tournament celebrated its inaugural First Nations Day, albeit only for 52 minutes as she beat 142nd-ranked qualifier Lucia Bronzetti 6-1, 6-1.
"It was nice for me to be a part of it in a way that I feel most comfortable," Barty, who has Indigenous heritage, said of the day dedicated to the Aboriginal and Torres Strait Islander people of Australia. "Out on the tennis court is how I express myself as an athlete, it's how I'm able to express myself as a person as well.
"On a day we're bringing cultures together, bringing people together ... it was great for me to be able to play a small role doing what I love."
Rafael Nadal didn't get it all his own way in the subsequent match on Rod Laver Arena, needing five match points before beating 126th-ranked German qualifier Yannick Hanfmann 6-2, 6-3, 6-4.
The sixth-seeded Nadal, aiming for a men's record 21st Grand Slam singles title, had two match points on Hanfmann's serve and two more on his own before finally clinching a spot in the third round when his rival sent a forehand long.
Nadal converted four of his 16 break-point chances, including one of eight in the third set, but only faced two break points on his own serve and fended them both off.
For the 35-year-old Nadal, after fatigue, injuries and illness curtailed his 2021 season following the French Open, time on court is more important than anything.
"I said here before the tournament started, things are not going to be perfect, but every day that I'm going to spend on court, the chances to play better are higher," he said. "After two matches is the moment to make a step forward. I'm excited about it."
Nadal shares the men's record of 20 singles titles with Roger Federer and Novak Djokovic, and he doesn't have either of them in the draw this time.
Federer is skipping the Australian Open while he continues his recovery from injury. Djokovic, a nine-time champion at Melbourne Park, was deported after an 11-day saga that he ultimately lost because he didn't meet Australia's strict COVID-19 vaccination regulations.
Miomir Kecmanovic, who was originally drawn to meet Djokovic in the first round, advanced to the third with a 7-6 (7), 7-5, 7-6 (8) win over Tommy Paul.
Olympic gold medalist Alexander Zverev, Wimbledon finalist Matteo Berrettini, No. 17 Gael Monfils and No. 23 Reilly Opelka advanced in straight sets.
In two marathon five-setters, No. 14 Denis Shapovalov held off Kwon Soon-woo 7-6 (6), 6-7 (3), 6-7 (6), 7-5, 6-2 in 4 hours, 25 minutes on Margaret Court Arena, and Sebastian Korda edged Corentin Moutet 3-6, 6-4, 6-7 (2), 7-5, 7-6 (6) in 4:47.
In the women's draw, French Open champion Barbora Krejcikova set up a third-round match against No. 26 Jelena Ostapenko, advancing along with No. 5 Maria Sakkari, No. 8 Paula Badosa and No. 15 Elina Svitolina, who next plays two-time Australian Open champion Victoria Azarenka.
Svitolina was leading 6-3, 5-7, 5-1 when Harmony Tan retired with a left leg injury, and waited on court until Tan was removed in a wheelchair.
"It's always horrible when any athlete gets injured in competition," Svitolina said. "It's tough to see a player going out like this."