Serena Williams lost the second U.S. Open tuneup match she competed in since she indicated she was likely to step away from tennis following the final Grand Slam of the year.

Williams fell in straight sets to reigning U.S. Open champion Emma Raducanu, 6-4, 6-0, at the Western & Southern Open in Ohio on Tuesday night.

The event was the second tuneup match ahead of the Grand Slam tournament in Flushing Meadows, N.Y. Williams lost to Belinda Bencic in straight sets last week in Toronto. Before her essay was published in Vogue magazine, she defeated Nuria Parrizas-Diaz for her first win since the 2021 French Open.

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Serena Williams and Emma Raducanu

Serena Williams, left, shakes hands with Emma Raducanu of Britain after their match during the Western & Southern Open tennis tournament on Aug. 16, 2022, in Mason, Ohio. (AP Photo/Aaron Doster)

Raducanu came into the tournament ranked No. 13 in the world. She hadn’t won a match since the Citi Open in Washington against Camila Osorio. She lost in straight sets to Camila Giorgi in the National Bank Open in Toronto.

Williams, 40, is set to walk away from the sport with 23 Grand Slam titles — the most in the Open Era and second most all-time behind Margaret Court. She will get one more chance to tie the court’s record. She lost in the first round of Wimbledon earlier in the summer.

Emma Raducanu looks on

Emma Raducanu of Britain reacts after winning a point against Serena Williams during the Western & Southern Open tennis tournament on Aug. 16, 2022, in Mason, Ohio. (AP Photo/Aaron Doster)

Williams admitted in the essay that there was no "happiness" in making the announcement, but she was ready for "what’s next."

"There is no happiness in this topic for me," she wrote. "I know it’s not the usual thing to say, but I feel a great deal of pain. It’s the hardest thing that I could ever imagine. I hate it. I hate that I have to be at this crossroads. I keep saying to myself, I wish it could be easy for me, but it’s not. I’m torn: I don’t want it to be over, but at the same time I’m ready for what’s next."

SERENA WILLIAMS LOSES FIRST MATCH SINCE ANNOUNCING RETIREMENT

Tennis legend John McEnroe told Fox News Digital over the weekend that Williams’ career was on par with some of the all-time greats.

"Serena’s the greatest female athlete, to me, in the history of sports. I don’t care who you could come up with. She’s one of the greatest athletes period — male or female. She’s put herself along the likes of Tom Brady, Michael Jordan, whoever you want to say. … She’s 40 years old. She’s done everything in tennis. She’s got nothing to prove," McEnroe said.

Serena Williams reacts

Serena Williams reacts after winning a point against Emma Raducanu of Britain during the Western & Southern Open tennis tournament on Aug. 16, 2022, in Mason, Ohio. (AP Photo/Jeff Dean)

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"It sounds like she wants to have more kids, awesome. She’s got a lot of other interests. People want to be a part of what she’s doing. She’ll be doing just fine. We were sort of expecting this to happen. She wanted to win a couple more, one or two more, break the all-time record, win a couple after having her daughter. That doesn’t look like it’s going to happen, but that, to me, doesn’t take away that she’s the greatest of all time."

The U.S. Open is set for Aug. 29 and will end on Sept. 11.

The Associated Press contributed to this report.