Sebastian Korda stared down Carlos Alcaraz on Sunday, sending the world No 1 crashing out of the Miami Open third round 6-3, 5-7, 6-4.
Korda, ranked 36th in the world, notched his first victory over a world No 1, sending Alcaraz to his second straight early exit in Miami following defeat to 55th-ranked Belgian David Goffin in the second round last year.
Since that defeat, Alcaraz had built a remarkable 73-6 record, including a 16-0 start to 2026 that included an Australian Open triumph to complete a career Grand Slam and a title in Doha.
It looked like Korda had missed his chance to spring the upset when he served for the match at 5-4 in the second set and was broken at love.
Alcaraz won the next two games to force a third set, part of a run of five straight games for the Spaniard.
But Korda didn't buckle, and it was the American who seized a break for 4-3 in the third when Alcaraz sailed a forehand wide.
He held his next service game with confidence, slamming down an overhead winner on game point and after Alcaraz held serve Korda served for the match again, this time making no mistake.
"It feels great," said Korda, who has been ranked as high as 15th in the world but has endured two seasons disrupted by injuries.
"I took the scenic route, that's for sure – a little more stress than I would want but happy with how I played, happy with how I stayed with it."
Alcaraz said Korda played an "incredible" match.
"A lot of tight, tight moments that I just didn't make the most of it," Alcaraz said. "I think he was better on those points, on those moments. I would say that was the key of the match."
Korda will face Spanish qualifier Martin Landaluce for a place in the quarterfinals after Landaluce ousted 14th-seeded Russian Karen Khachanov 6-3, 7-6 (7/2).
SABALENKA MARCHES ON
World No 1 Aryna Sabalenka kept her title defense on track with a 6-4, 6-2 victory over 72nd-ranked American Caty McNally that was tougher than the score indicated.
They were on serve after exchanging four breaks in the opening set when Sabalenka gained the decisive break in the final game.
The Belarusian star, trying to complete the "Sunshine Double" after capturing her first Indian Wells title last week, wasted one chance to break in the second set before ramping up her return pressure to break McNally's on her last two service games.
"She played really great tennis," Sabalenka said, adding that her hold for 5-4 in the opening set, in a game that went to deuce five times, was key.
"(I'm) super happy to close this match in straight sets," said Sabalenka, who booked a meeting with China's Olympic gold medallist Zheng Qinwen a 6-2, 6-4 winner over Madison Keys.
It was Zheng's first win over a top-20 player since elbow surgery last July.
World No 2 Elena Rybakina, who beat Sabalenka in the Australian Open final but fell to her in the Indian Wells title match, moved smoothly into the last 16 with a 6-3, 6-4 victory over Ukraine's Marta Kostyuk.
Rybakina next faces Australian qualifier Talia Gibson, who knocked off another seed with a 6-2, 6-2 victory over 18-year-old 18th seed Iva Jovic.
Gibson, who reached the quarterfinals at Indian Wells, had ousted former world No 1 Naomi Osaka in the second round.