Who Is Harmony Tan, the Player Who Beat Serena Williams at Wimbledon?

The matchup seemed lopsided on paper.

Serena Williams, possibly the greatest tennis player ever and the winner of the most Grand Slam singles titles in the Open Era, matched up with Harmony Tan, No. 115 in the world, in the first round of Wimbledon.

Tan, playing in her first Wimbledon, had not advanced further than the second round in any of her six previous appearances at a major. Even Tan admitted in her on-court interview that she was “really scared” upon seeing that she was scheduled to face Williams and had hoped she could win one or two games Tuesday.

Williams was asked in a news conference ahead of the match if she was disappointed that she didn’t draw a more challenging opponent.

“Every match is hard; every match,” said Williams, who was competing in her first singles match on tour since tearing a hamstring in last year’s opening round of Wimbledon and retiring from the match. “You can’t underestimate anyone or any match.”

Tan, 24, proved Williams’s words true, spoiling her return to tennis and quest for a record-tying 24th Grand Slam singles title. Tan defeated Williams, 7-5, 1-6, 7-6 (10-7). For Williams, 40, the loss was the second of her career in the first round of Wimbledon.

Tan, a Paris native with Cambodian and Vietnamese parents, said she watched Williams often while growing up. Tan turned professional when she was just 14, but this was her first matchup against Williams, and she had never faced a player with career accomplishments even approaching those of Williams.

The highest-ranked player she has faced is Elina Svitolina of Ukraine, who was No. 17 in the world at the time of their matchup at this year’s Australian Open. Tan retired in the third set of the match after suffering an injury.

For this matchup with Williams, Tan had a slight advantage in the form of her coach, Nathalie Tauziat.

Tauziat, the 1998 Wimbledon women’s singles runner-up, who was ranked as high as No. 3 in the world, faced Williams three times, beating her once at the Paris Open final in 2000. Tan didn’t mention in her post-match interview whether or not Tauziat gave her specific pointers based on her experience against Williams. Still, she thanked Tauziat for supporting her after the win.

“I’m really surprised today,” Tan said of her win in the on-court interview.

She will have the opportunity to advance past the second round in a Grand Slam tournament for the first time in her career when she faces Sara Sorribes Tormo, a Spaniard seeded 32nd. The two faced each other earlier this year in Monterrey, Mexico, with Tan losing, 6-2, 6-2.