World No. 1 Naomi Osaka defeats Magda Linette in straight sets 6-2, 6-4 to advance to the third round of the US Open. (1:42)

NEW YORK -- Naomi Osaka smacked a forehand winner into the open court, bringing Colin Kaepernick and Kobe Bryant to their feet in applause.

Osaka has power in her strokes and star power in her corner.

The defending US Open champion moved into the third round Thursday with a 6-2, 6-4 victory over Magda Linette, setting up a possible third-round showdown with Coco Gauff.

Wiith Kaepernick and Bryant sitting with her team just a few rows off the Louis Armstrong Stadium court, Osaka did her part.

Kaepernick, the former San Francisco 49ers quarterback who three years ago began kneeling during the national anthem before games to protest social injustice, has been working out in the area in hopes of getting another shot in the NFL. Bryant, the retired NBA superstar, came to the US Open on Thursday to promote "Legacy and the Queen,'' a new book that he conceived and that Osaka has supported.

Kobe Bryant and Colin Kaepernick cheered on Naomi Osaka. AP Photo/Eduardo Munoz Alvarez

Osaka, 21, was grateful for their attendance, she said, and motivated to win quickly so she wouldn't keep them in the sun too long watching.

"It's just funny to me. You know, like, last year compared to this year there is no way Kobe would sit in my box," Osaka said. "Yeah, Kaepernick, too. It's just crazy who you run into in life.

"For me, it wasn't pressure. It was just like I really didn't want them to sit in the sun too long, honestly. That was the thing that was on my mind. I was, like, I don't really want to play a third set."

Osaka said she had never met Kaepernick until just before the match, but that she knows Bryant and goes to him for "real life" advice.

"He's someone I look up to as an athlete and also as a person," Osaka said. "I'm really grateful that I even have the opportunity to talk to him and stuff."

The No. 1 seed gave her famous guests plenty to cheer along the way, especially the forehand winner on break point that gave her a 4-3 lead in the second set after Linette had grabbed the first three games.

The 15-year-old Gauff defeated qualifier Timea Babos in the leadoff night match on Armstrong to advance to a third-round meeting with Osaka.

"It's amazing at that age," Bryant said. "Not just the skills she possesses, but the poise."

Osaka said she would welcome the opportunity to play against Gauff.

"Off the court she seems like me," Osaka said. "Well, she seems a little bit more, like, she knows what she's doing. I just mean, like, I'm very quiet. I've gotten actually a bit talkative recently, though. But, yeah, I saw her in the locker room. She wasn't really talking to anyone. I was, like, 'Oh, looks familiar. I'm just going to talk to her.'

"She's super sweet and I would love to play her."

Another top seed went down earlier in the day. Two-time Grand Slam champion Petra Kvitova, seeded No. 6, was upset by Andrea Petkovic 6-4, 6-4.

No. 19 seed Caroline Wozniacki advanced to the third round of the U.S. Open, fighting back a challenge from American Danielle Collins to win 4-6, 6-3, 6-4.

Wozniacki, last year's Australian Open champ and a two-time runner-up at Flushing Meadows, struggled to find her rhythm early against the hard-hitting Collins.

But she settled down in the next two sets, while the 35th-ranked Collins became more erratic, making 18 unforced errors in the final set and 46 for the match.