NEW YORK -- In the middle of her comeback win in the third round of the US Open, Coco Gauff made the mistake of looking up. The 19-year-old American was trying to catch her breath and regroup on the changeover when she saw Justin Bieber and his wife Hailey on the screen. 

"I saw them immediately on the Jumbotron," Gauff said after her three-set win over Elise Mertens. "I don't know if the camera saw me looking up. I hoped if I lost the match, they weren't going to blame it on that."

Gauff said her mind was everywhere as she scrambled to engineer her eighth consecutive win and second comeback in her last three matches. But that's actually not a bad thing. 

"I was thinking about the Renaissance Tour during my match," Gauff said. "I think about a lot of different things.

"Honestly, it keeps me relaxed. I don't know if it's a coping mechanism or what. I thought about Marvel today. Obviously the Biebers. There was a lot of things I was thinking about."

Obamas, BJK, Sharapova take in opening night at the US Open

Gauff is settling in nicely in the cavernous stage of Arthur Ashe Stadium. Her two night session matches have been crowd-pleasers that have brought out A-list celebrities like Barack and Michelle Obama, Jimmy Butler and Katie Holmes. 

"I'm really honored that people spend Friday night watching me play tennis," she said.

"Jimmy Butler, he's come to a couple of my matches. I still am like, Man, this guy is busy, why is he coming to watch me play?"

Gauff was over the moon when she got to meet the Obamas after her first-round win and she admitted to being starstruck when she saw the Biebers. 

But there's only one celebrity that Gauff says might derail her if she saw them mid-match. 

"Definitely Beyonce," Gauff said. "If she ever came, oh, my goodness, I hope they would not show her on the screen. Maybe at the end.

"No tennis atmosphere matches nighttime on Ashe, honestly. I've played in pretty much all of them at this point, and there's nothing that compares to Arthur Ashe at night."