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Elena Rybakina defeated Serena Williams 6-3, 7-5 in the fourth round of the 2021 French Open on Sunday. The 21-year-old Rybakina advanced to the quarterfinals with the win, and in the process denied Williams a chance to continue her quest for a 24th career Grand Slam singles title, something she's been after for three years now.

A 23-time Grand Slam champion, Williams is still searching for the elusive record-tying 24th title. Prior to Sunday's upset, it was looking like Williams' road to Grand Slam No. 24 had opened up with many top seeds out of the tournament.

The No. 21 seed Rybakina will face No. 31 seed Anastasia Pavlyuchenkova in the quarterfinals. Pavlyuchenkova defeated No. 15 seed Victoria Azarenka in the fourth round. Rybakina's win over the seventh-seeded Williams is her first top-10 win at a Grand Slam and fifth overall. So far through the clay surface tournament, Rybakina has not dropped a set.

Rybakina broke Williams five times in the straight sets victory, and finished with 21 winners and 13 unforced errors. Williams finished the loss with 15 winners and 19 unforced errors. Rybakina showed composure on the court, besting Williams in net points won (86 percent compared to Williams' 50 percent) and break points won (71 percent compared to Williams' 60). Playing in the French Open for just the third time, Rybakina boasted a strong baseline game and steady serve to get past Williams.

The clay surface at Roland Garros is not Williams' strongest, and the French Open is where she's won the fewest Grand Slam titles in her career. Williams has won three French Open titles, with the last one coming in 2015 when she bested first-time Grand Slam finalist Lucie Safarova in three sets. That's compared to her six US Open titles and seven at the Australian Open and Wimbledon. Williams hasn't made it past the fourth round at the French Open since she finished runner-up in 2016.

There are two more Grand Slam tournaments left in the 2021 tennis calendar with Wimbledon in London (June 28-July 11) and the US Open in New York (Aug. 30-Sept. 12). Wimbledon is played on grass, while the US Open is a hard-court tournament, both of which are Williams' strongest playing surfaces.

If Williams were to win her equalizing 24th title at Wimbledon, then that would leave her one more chance this season (at the US Open) to surpass Margaret Court's record before Williams turns 40 on Sept. 26. Williams had lost back-to-back Wimbledon finals to Angelique Kerber and Simona Halep in 2018 and 2019 before the tournament was canceled last summer because of the global coronavirus pandemic. 

In the women's singles draw at the French Open, American No. 4 Sofia Kenin and No. 8 Iga Swiatek are only top-10 seeded players remaining. Along with Kenin, there are two more American women left in the tournament, with No. 24 seed Coco Gauff and Sloane Stephens both advancing to the fourth round.