With the Obamas and Biebers, Aaron Rodgers and Aaron Judge, the US Open stars aren't just on court

WATCH: Rob Gronkowski watches, then meets Coco Gauff at the US Open | The Break

NEW YORK (AP) — Coco Gauff glanced up at one of the 35-foot-wide video boards high atop Arthur Ashe Stadium during a US Open match last week and caught a glimpse of celebrity couple Justin and Hailey Bieber.

"I saw them immediately on the jumbotron. I don't know if the camera saw me looking up," said Gauff, who was scheduled to play in the quarterfinals in Ashe on Tuesday. "I hoped if I lost the match, they weren't going to blame it on that."

The stars aren't just on the court at Flushing Meadows, where the see-and-be-seen set is also in the suites and seats in the 23,000-plus-seat main arena. From the Biebers to the Obamas, from New York Jets quarterback Aaron Rodgers to New York Yankees slugger Aaron Judge, from retired ski racer Lindsey Vonn to director Spike Lee, the bold-faced names keep swinging by the US Open.

"Some of them have a passion for tennis. Some of them want to see a specific player," U.S. Tennis Association spokesman Chris Widmaier said. "Frances Tiafoe brings people that want to see him. Coco Gauff, for sure. Novak Djokovic, too. No disrespect to any of them, but Roger Federer and Serena Williams were at a different level. When it comes to famous people wanting to watch famous people play, no one comes close to those two."

For the celebs, it's a chance to see some high-level tennis for free and get some free publicity.

For the tournament, it's a chance to gain an extra bit of attention and position itself as an aspirational event.

Sometimes the famous folks ask for tickets. Sometimes they're invited by the USTA, which uses an outside firm to help contact publicists, managers and agents and will provide rides to and from the tournament.

"If we know somebody's in town—maybe they're shooting a movie, maybe they're shooting a television series, maybe they're here for the (MTV Video Music Awards)—and we have a relationship with the person who handles them," Widmaier said, "we might say, ‘Hey, by the way, if so-and-so is interested, we'd love to host them if their schedule permits.'"

And sometimes a player issues the invitation.

Tiafoe, a 25-year-old from Maryland on Tuesday's quarterfinal schedule, arranged for rapper Pusha T to be at one of his matches this year.

"My agent took care of him. I got him courtside. That was pretty cool," Tiafoe said. "As soon as I saw him there ... I wanted to dap him up and say thanks for coming out. It was good. Obviously the US Open put that on Instagram right away. Pretty smart."

Make no mistake: The players are aware of who's there.

"I notice when they're watching," said defending men's champion Carlos Alcaraz, who won in front of singer J Balvin and actor Ben Stiller on Monday. "Sometimes, (I think), ‘Oh, my God, he's there or she's there.' It's crazy."

Yes, the celebrities from the worlds of entertainment, politics and other sports are a hit with the players—especially if they can connect after a match.

"I was definitely starstruck with Justin Bieber. ‘Never Say Never' was ... one of my favorite songs when I was a kid. Then ‘Baby, Oh, Baby.' I could go through all his songs. Then Hailey, too, coming," said Gauff, a 19-year-old from Florida. "I guess it was a little date night for them, which was really cool."

She had met first lady Michelle Obama previously, but not former President Barack Obama, and was thrilled to get to chat with both after they watched her win on the tournament's opening night.

"I wasn't sure they were here or not. I saw the Secret Service. I didn't know if it was Mr. Biden and Mrs. Biden. I knew it was somebody. Then I heard that maybe Mr. Clinton was coming. I didn't know who exactly it was. So I didn't know until after the match," Gauff said. "I'm going to never forget that moment for the rest of my life."