Garbine Muguruza won her first Grand Slam title by beating defending champion Serena Williams 7-5, 6-4 at the French Open on Saturday, denying the American her record-equaling 22nd major trophy.

The fourth-seeded Muguruza, a 22-year-old from Spain, used her big groundstrokes to keep No. 1 Williams off-balance and overcame signs of nerves in the form of nine double-faults to pull off the surprise.

Muguruza also managed to deal with Williams’ dangerous serve, breaking three consecutive times from late in the first set to early in the second.

This was Muguruza’s second major final; she lost to Williams at Wimbledon last year. But Muguruza has won her past two matches against Williams on the clay of Roland Garros, including in the second round in 2014.

For Williams, whose timing was not exactly right much of the afternoon, Saturday’s loss delayed yet again her pursuit of matching Steffi Graf with 22 Grand Slam singles championships, the most in the Open era, which began in 1968. Margaret Court holds the all-time record of 24.

Williams got No. 21 at Wimbledon in 2015, her fourth major title in a row. But since then, she has been beaten in the semifinals at the U.S. Open by Roberta Vinci last September, in the final at the Australian Open by Angelique Kerber in January, and now by Muguruza. This is the first time in Williams’ career she has lost back-to-back Grand Slam finals.

This year’s visit to Paris hardly could have started off more inauspiciously for Muguruza: She lost the very first set she played in the tournament, against 38th-ranked Anna Karolina Schmiedlova.

But, oh, how Muguruza turned things around from there. She won the next 14 sets she played, displaying the deep groundstrokes and take-the-ball-early aggressiveness that flustered Williams.

The final began under a slate ceiling of clouds, but at least there was none of the heavy rain that led to flooding in Paris and a temporary shutdown of the Louvre museum. All those showers jumbled the tournament schedule, forcing Williams to be in action for a fourth straight day in the final.

Muguruza won the prematch coin toss and let Williams serve first, a fascinating choice given that Williams is widely regarded as the best server in the women’s game, perhaps ever. And the decision seemed only more dubious as Muguruza managed to put the ball on play on only one of the first six points Williams served. On one early point, Muguruza whiffed completely on an attempted backhand return of an 89 mph (143 kph) high-kicking second serve.

And yet, it all wound up working out. And how.