USTA spokesman Brendan McIntyre said adding a 15th day of singles can not only "provide more fans the opportunity to see main draw singles competition in person, but also gives fans around the globe the opportunity to watch (on television) on a weekend day and night".

No 6 seed Ben Shelton was the opening act in Ashe at noon on Sunday, and said before his 6-3, 6-2, 6-4 victory over Peruvian qualifier Ignacio Buse that he understood why tournaments would want an extra weekend day of ticket sales — and he was pleased to be on the side of the men's draw that went first.

Still, there are players, such as Thompson, two-time US Open semifinalist Frances Tiafoe or Matteo Arnaldi of Italy, who said it's a mistake to set things up so that someone who makes a tournament debut on Sunday and wins wouldn't play again until Wednesday, a change to the every-other-day rhythm at the Slams.

"I mean, I get it," Tiafoe, an American who is seeded 17th, said about the Sunday opening. "Why not? If you can make money on a day and get the guys out there, and we're already all here anyway (on what used to be) kind of a dead day, it's not a bad thing. But, two days off that early in a Slam? It's a little weird."

Agencies via Xinhua