Coco Gauff is a notable beneficiary as Angelique Kerber and Maria Sharapova have been forced out of the Luxembourg Open.
Serena and Venus Williams lost three games between them as the American pair cruised through to the second round at Flushing Meadows.
"I don't know who that is," Serena Williams said when asked about Carlos Ramos at the US Open.
Serena Williams needed just 59 minutes to thrash Maria Sharapova at the US Open.
Serena Williams against Maria Sharapova headlines the best first-round ties at the US Open, but there are plenty of other notable match-ups.
The first round of the US Open served up a showdown between two former champions, with Serena Williams to face Maria Sharapova.
It was a good day for the seeds at the Western & Southern Open as Naomi Osaka, Simona Halep and Ashleigh Barty advanced.
Caroline Wozniacki was no match for Dayana Yastremska, while Maria Sharapova reached the second round on Monday.
Maria Sharapova – a five-time grand slam champion – was eliminated following a two hour, 41-minute thriller in Toronto on Monday.
Maria Sharapova, Venus Williams and Angelique Kerber have achieved a feat that Simona Halep has in her sights at SW19.