NEW YORK — Serena Williams was a bit shaky at the start of her U.S. Open semifinal.

For all of six minutes.

That’s how long it took her to drop the opening two games. Williams spent the next hour playing flawlessly, particularly up at the net, grabbing 12 of 13 games to beat No. 19 seed Anastasija Sevastova of Latvia 6-3, 6-0 and reach her ninth final at Flushing Meadows and 36th at all Grand Slam tournaments.

“I’ve been working hard on my volleys. I have won a few doubles championships so I know how to volley,” Williams said with a laugh, before adding this punch line: “I just usually come in only to shake hands.”

With one more win, Williams will earn her seventh U.S. Open championship and 24th major singles trophy, equaling Margaret Court for the most in tennis history.

On Saturday, Williams will face 20th-seeded Naomi Osaka of Japan, who beat 2017 runner-up and No. 14 seed Madison Keys in the other semifinal, 6-2, 6-4.

Williams had lost in the semifinals in her previous two trips to New York – against Roberta Vinci in 2015 while bidding for a calendar-year Grand Slam, and against Karolina Pliskova in 2016. A year ago she missed the U.S. Open because she gave birth to her daughter, then dealt with complications related to blood clots.

The American returned to the tour in February and to Grand Slam action at the French Open in May, when she had to withdraw from the field with an injured chest muscle. At her second major back, Wimbledon, she was the runner-up.

Now comes a chance to take a title and become, a few weeks shy of turning 37, the oldest woman to win a Slam in singles.

“It’s honestly really incredible. A year ago I was fighting for, literally, my life at the hospital after I had the baby,” Williams said, her voice wavering. “So every day I step out on this court, I am so grateful that I have an opportunity to play this sport, you know? So no matter what happens in any match – semis, finals – I just feel like I’ve already won.”

The roof was closed hours earlier because of a forecast calling for rain and strong wind, and so the screams and applause reverberated through the place whenever spectators roared for Williams, during the pre-match introductions, when she stepped to the baseline to serve in the opening game, and then after nearly every point she won.

And there were plenty of those.

Total winners? Williams led 31-10 in that category. And Sevastova’s penchant for drop shots did not pay off: She lost three points in the first set alone with miscues that landed on the wrong side of the net.

“She got a little bit lucky, I think, on some breaks in the first set. Then she started feeling better. When she’s in front, it’s tough to play,” said Sevastova, who retired from tennis in 2013, then returned to the tour in 2015.