Aryna Sabalenka, ranked second in the world, suffered an unexpected loss to Emma Navarro in the fourth round of Indian Wells.
Belarusian Sabalenka, who secured her Australian Open title defense in January, suffered a 6-3 3-6 6-2 defeat against the 23rd seed.
Navarro, fueled by the support of the California crowd, advanced to her inaugural WTA 1000 quarter-final.
Meanwhile, fellow American and third seed Coco Gauff dominated with a 6-0 6-2 victory over Belgium’s Elise Mertens.
Celebrating her 20th birthday on the court, the 2023 US Open champion Gauff swiftly secured the first set in just 25 minutes.
Although Mertens managed to break and hold serve to equalize the second set at 2-2, Gauff regained control, winning four consecutive games to secure her spot in the quarter-finals for the second consecutive year.
“I feel really good. That’s my best match of the tournament so far and I’m obviously happy to get the win on my birthday,” Gauff told Sky Sports.
Gauff and Navarro are bidding to become the first American women to win at Indian Wells since Serena Williams in 2001.
Gauff is set to face China’s Yuan Yue in the semi-finals, who defeated Russian 11th seed Daria Kasatkina 4-6 6-4 6-3.
On the other hand, Navarro will take on Greek ninth seed Maria Sakkari, who secured a 6-2 3-6 6-3 victory over France’s Diane Parry.
In the match, Navarro clinched the first break in the eighth game, saving a break point before securing the opening set with a serve. However, Sabalenka rallied to claim the second set.
After exchanging early breaks in the decider, Navarro took a 3-1 lead as Sabalenka struggled with her serve. Despite saving the first match point, the two-time major winner missed the second, resulting in Navarro’s biggest career victory.
This win adds to the 22-year-old’s successful season, which began with her first WTA Tour title in January at the Hobart International.
“I’m feeling really good. It’s never easy coming out and playing an opponent like that – so experienced and just so talented,” Navarro said.
“She made it really tough on me today, but I was glad I was able to play some good tennis in the big moments.”
Russian fourth seed Daniil Medvedev secured a 6-4 6-4 triumph against Bulgaria’s Grigor Dimitrov, advancing to the men’s quarter-finals.
Medvedev is set to take on Danish seventh seed Holger Rune, who saved a match point en route to a 2-6 7-6 6-3 victory over American 12th seed Taylor Fritz.
Notably, Indian Wells stands as the sole hard-court ATP Masters 1,000 tournament that Medvedev has yet to win.
Norway’s ninth seed Casper Ruud overcame Frenchman Gael Monfils 3-6 7-6 (7-3) 6-4, securing a spot in the last eight.
Ruud will meet American Tommy Paul in the quarter-finals, who defeated Italy’s Luca Nardi with a score of 6-4 6-3. Nardi had previously eliminated world number one Novak Djokovic in the previous round.