Today is a very special day in the tennis world, as one of the sport’s biggest icons, Serena Williams, turns 39—and it comes on the eve of Roland Garros, her 10th major back on tour as a mom.

“I honestly never thought I would be playing at my age,” Williams told reporters in Paris on her birthday. “I mean, I don’t quite look 39. But yeah, I don’t know when it’s going to stop for me. I just have fun. When I feel it’s over, it’s over.

“But I could have guaranteed and pretty much bet my life that I would not have been playing at 39. This is why I don’t bet.”

Williams has been unable to win the elusive 24th Grand Slam singles title, but she’s come extremely close, reaching four finals—Wimbledon and the US Open in 2018, then Wimbledon and the US Open again in 2019. She very nearly made a fifth final in Flushing Meadows two weeks ago, holding break point for a 6-1, 2-0 lead against Victoria Azarenka in the semifinals before falling, 1-6, 6-3, 6-3.

“I think a semifinal is always great,” Williams said about the result, but added: “Is it great for me? Absolutely not. That’s just how I feel. That’s how I always feel. It is what it is.

“I’m happy that I can feel that way. And really there was nothing I could do. Yeah, there was nothing I could do in the end. It was what it was. I mean, I’m in a position in my career where I cannot be satisfied. I don’t want to sit here and say, Oh, I’m happy. Because I’m not.”

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