Serena Williams ousted in French Open's fourth round by a serene Elena Rybakina

WATCH: Highlights of Elena Rybakina's 6-3, 7-5 defeat of 23-time Grand Slam champion Serena Williams.

Sunday, June 6 began as a day to celebrate legends and ageless excellence in our sport. Six-time Roland Garros champion Bjorn Borg turned 65. Less than an hour after midnight, 39-year-old Roger Federer advanced to the fourth round. Another 39-year-old, Serena Williams, also in the round of 16, geared up to play the final match of the day session on Court Philippe Chatrier.

Though no one knew it at the time, Borg played his last match here 40 years ago, one day after he turned 25. This afternoon in Paris, Federer opted to let his words, rather than his racquet, signal his departure. Approximately three hours later, Williams exited Roland Garros the conventional way, beaten 6-3, 7-5, in 78 minutes by 21st-seeded Elena Rybakina.

It was the 21-year-old Rybakina’s first win over a Top 10 player at a major.

“I'm so happy with the match today,” said Rybakina. “Of course when I went on court I didn't expect anything. I just had set plan, which we discussed with my coach. I just tried to follow it. It worked out today.”

As Rybakina explained after the match, the strategy called for attacking Williams’ backhand, mixing up serves and playing aggressively. It worked superbly. Backed by compact, flat strokes and excellent court coverage skills, Rybakina dictated the tempo right from the start, taking a 4-1 lead.

Her only hesitancy came when she appeared to stop playing the ball and became aware of the occasion and the resume of the opponent. Prior to this year, Rybakina had played only twice in the main draw of Roland Garros and won only one match. Now, in Chatrier versus Williams, the possibility of reaching her first Grand Slam quarterfinal loomed as a delicious reward.

So it was that Rybakina double-faulted at 4-2, 30-30 and was eventually broken. But she rebounded sharply, taking Williams’ serve in the next game with a sharp forehand up the line to serve for the set at 5-3. At 40-30, Rybakina double-faulted. But at last, she closed it out on her fourth set point when Williams lined a backhand wide.

I'm so close,” Serena said. “There is literally a point here, a point there, that could change the whole course of the match. I'm not winning those points. That like literally could just change everything.

Typically, such a deficit triggers a forceful counterattack from Williams. Today, though, it only came in fits and starts. Twice in the second set, Williams went down a break, rallying back each time. But then, serving at 5-all, everything moved at warp speed as four straight points all going Rybakina’s way:

• an untouchable forehand down the line return
• a sharply whipped crosscourt forehand on the run that elicited an error
• a double-fault
• a hard and deep crosscourt backhand return that generated another Williams miss

Having come through boldly at this critical late stage, Rybakina remained focused. Serving at 6-5, love-15, she struck an ace and then maintained enough consistency as three shots from Williams sailed long, the final one a backhand return.

“Yeah, I think I would have just played harder and played better,” said Williams. “I don't know. Just played, I don't know, better, I guess? I hate regretting, though. But I definitely would have just tried to do that.”

The business-like way Williams addressed this defeat makes sense. Like Federer, she too knows her chances for success at Roland Garros are much less than they are at Wimbledon. But prior to arriving in Paris, she’d only played three matches since the Australian Open. Here at Roland Garros, she got in four.

Encouraged by getting in ample match play, Williams feels she is on the verge of finding her best form.

“I'm so close,” she said. “There is literally a point here, a point there, that could change the whole course of the match. I'm not winning those points. That like literally could just change everything.”

For Williams, it’s on to Wimbledon, including the pre-event quarantine. For Rybakina, it’s a career highlight, but, per usual for her, nothing to get too excited about—at least on the surface.

“I'm really calm person, but on top of this, all my nerves inside sometimes is good,” she said. “Sometimes of course it's not, because to hold everything inside it's not possible. One day it's going to explode, and who knows when, so it's dangerous for other people, especially close ones.”

Recruited by 15 colleges in America, Rybakina chose instead to turn pro. Asked by WTA Insider Courtney Nguyen in early 2020 to cite her idol, Rybakina said, “Roger Federer and still Roger Federer.”

But on this day when legends like Federer began the news cycle, Rybakina was the one who made a major headline of her own.