Japan's Naomi Osaka downed defending champion Angelique Kerber before facing a more time-consuming task tracking down her family movements.
"My sister is in Florida training. She told me she was watching my match, because she sent me a lot of messages and stuff. And my mom, apparently she was here. I saw her after my match, and I was, like –I was so surprised.
"But my dad is here too, but he doesn't watch my matches. He just pops up at the end and says, Congratulations, and then that's it," said Osaka.
French Open champion Jelena Ostapenko played under the Arthur Ashe Stadium roof for the first time, but wished she could have stayed longer.
Ostapenko defeated Spain's Lara Arruaberrena 6-2, 1-6, 6-1 in a match relocated from Court 17 to Ashe because of rain.
The Latvian then won 12 of the last 14 points played on the showpiece arena to seal the deal in a tie suspended at 3-1 in the final set five hours earlier.
Ostapenko has a fan in giant basketball star, and fellow Latvian, Kristaps Porzingis, who plays for the New York Knicks. The 22-year-old was quick to praise Ostapenko's Roland Garros win on Twitter.
"I knew that he followed me on Instagram, so that's really cool. It's great that he posted that I won the French Open. I know he plays here in New York City, maybe he'll be here during the US Open and we'll have a chance to meet."
Meanwhile Roger Federer made a narrow escape in a tense five-set thriller Tuesday, sorting out worries about a back injury and poor preparation to reach the second round of the US Open.
The 19-time Grand Slam champion outlasted 70th-ranked US 19-year-old Frances Tiafoe 4-6, 6-2, 6-1, 1-6, 6-4 in a shockingly tough battle that boosted his hopes of a deep run on the New York hardcourts.
"I think this is going to give me a lot of confidence," Federer said. "It's important to go through all of these emotional roller coasters early. That pressure is not fun but it's what you have to go through."
The match was Federer's first since losing the Montreal final to Alexander Zverev nearly three weeks ago. He withdrew from Cincinnati with a sore back the following week.
"I was worried in the beginning from my back issue from a couple weeks ago but I loosened up," Federer said, calling his back "extremely well" and adding "it's only going to get better from here."
"To get through a five-set match you've got to be healthy. I believe this is going to give me great confidence in my game and my body."
Third seed Federer will next meet either Russia's Mikhail Youzhny, who is 0-16 against him, or Slovenia's Blaz Kavcic, 0-1 against Federer, as the Swiss chases a record sixth US Open crown.
The 36-year-old Swiss, who won this year's Wimbledon and Australian Open crowns, took the US Open titles from 2004-2008. The intense match came after limited preparation due to his back issues.