Eighth-seeded Madison Keys was forced to stay up late before overcoming fellow American Alison Riske to close out Monday’s play at Arthur Ashe Stadium on a busy opening day for the home tennis contingent at the US Open.

Keys, who reached the Australian Open semi-finals and Wimbledon quarter-finals last year, reined in her sometimes over exuberant groundstrokes to claim a 4-6 7-6 6-2 win over the 60th-ranked Riske in a grueling two hour, 25 minute slugfest.

With the night programme delayed by more than an hour following a ceremony to mark the opening of the tournament, the final match ended at 1:48 am, making it the latest women’s match ever at the Open.

“I just looked up and it’s almost 2 (am),” the 21-year-old Keys laughed in a post-match interview.

“Who wants to go party?”

After years of hand-wringing over the state of US tennis other than mighty women’s world number one Serena Williams, talent from the junior ranks is beginning to emerge.

At the start of play, 39 Americans were in the main draw, one fewer than the record set in 2005, and by the end of the day, nine of them had advanced but 14 had already been eliminated in first round action.

Next up for Keys, who twice received treatment on her right shoulder, is another American, 16-year-old Kayla Day, the US national junior champion and youngest player in the draw.

On the men’s side, two established American players, John Isner and Jack Sock, avoided upsets, fighting off challenges from highly touted 18-year-olds.

Big-serving Isner, the top-ranked American in the draw at number 21, roared back from two sets down to beat Frances Tiafoe 3-6 4-6 7-6 6-2 7-6.

Other results: (Women) Halep bt Flipkens 6-0, 6-2; Allertova bt Ivanovic 7-6 6-1; (Men) Nishikori bt Becker  6-1 6-1 3-6 6-3.