World No 2 Alexander Zverev was knocked out of the Madrid Open in the round of 16 by Argentina's Francisco Cerundolo on Tuesday as defending women's champion Iga Swiatek had a few scares before advancing to the quarterfinals.
Cerundolo, ranked 21, beat the German -- a two-time former winner in Madrid -- 7-5, 6-3 to repeat his feat from last year.
Swiatek reached her fifth WTA 1000 quarterfinal of the season with a hard-fought 6-0, 6-7 (3/7), 6-4 victory over 13th-seeded Diana Shnaider.
Argentinian Cerundolo will face Jakub Mensik in the quarterfinals after the Czech's straightforward 6-3, 6-2 victory over Kazakhstan's Alexander Bublik.
"I didn't play terrible, he just played better than me," Zverev said.
Matched game for game in the first set, Zverev offered up two set points to Cerundolo, who took the opening set at the second time of asking.
An over-hitting Zverev was broken immediately in the second set, allowing the 20th seed an advantage he built on to lead 4-1.
Zverev flung his racket to the ground in frustration, but Cerundolo kept his calm and served out for the match.
"I'm super happy because I know he loves playing here. He told me last year when I beat him," said Cerundolo.
"He's an incredible player. I have a great relationship with him, so super happy to get another win and to be in the quarter-finals again."
After a nationwide blackout cancelled the majority of play at the Caja Magica on Monday, power was restored at the venue on Tuesday morning, with matches commencing at midday.
Bulgaria's Grigor Dimitrov finally completed a 6-4, 7-6 (7/3) win over Britain's Jacob Fearnley, converting his third match point some 27 hours after his first.
The match was suspended on Monday with 15th seed Dimitrov leading 6-4, 5-4. When play resumed on Tuesday, both players held serve before Dimitrov edged the tie-break.
"That shows you how quickly anything can change, in life as well. From one point, you're serving for the match, from the other you're about to receive, and then the lights went out," said Dimitrov, who will face lucky loser Gabriel Diallo in the fourth round.
Former finalist Matteo Berrettini retired after dropping the opening set tiebreak to Jack Draper due to an abdominal injury.
Draper will face American Tommy Paul in the last 16.
Sixth-seeded Alex de Minaur defeated Canadian Denis Shapovalov 6-3, 7-6 (7/3) and next meets Italian Lorenzo Musetti.
Recording his 24th win of the season, the Australian has now tied Carlos Alcaraz for the most victories on tour in 2025.
Frances Tiafoe, the 16th seed, beat Alexandre Muller 6-3, 6-3 to book a fourth-round meeting with Novak Djokovic's conqueror, Matteo Arnaldi.
SWIATEK PUSHED, SABALENKA COASTS
In the women's tournament, Swiatek saved 11 of 13 break points en route to a two-hour 34-minute victory that sent her through to a last-eight showdown with Australian Open champion Madison Keys.
Asked about the power outage, the 23-year-old Swiatek admitted she enjoyed being off the grid for a few hours.
"Honestly, I liked yesterday, I think the whole world was more relaxed kind of, obviously the people who didn't lose because of this. I had time to rest," said Swiatek.
"Honestly, I just chilled and used the time not thinking about what I should do."
Women's world number one Aryna Sabalenka eased past 44th-ranked American Peyton Stearns 6-2, 6-4 to reach the last eight.
The 26-year-old Belarusian, who won in Miami in March, will next face either Ukrainian Marta Kostyuk or Russian Anastasia Potapova.
Sabalenka has won two titles in Madrid in 2021 and 2023 and reached the final last year.