World number two Aryna Sabalenka made light work of 16-year-old Mirra Andreeva on Monday with a 6-3, 6-1 win to reach the Madrid Open quarter-finals.
Iga Swiatek, top of the world rankings, followed her into the last eight with a hard-fought three set win over Ekaterina Alexandrova, 6-4, 6-7 (3/7), 6-3.
In the men's tournament world number three Daniil Medvedev beat his friend and Russian compatriot Alexander Shevchenko, while Frances Tiafoe and Cameron Norrie crashed out against underdogs.
Russian youngster Andreeva, a wildcard, became only the third 15-year-old to win a WTA 1000 main draw match when she beat 2021 US Open finalist Leylah Fernandez last week.
She went on to beat two top 20 players in Beatriz Haddad Maia and, on her 16th birthday, Magda Linette, but overcoming 2021 Madrid winner Sabalenka was a bridge too far.
"Of course I'm happy with the win, I wish I would have played at Madrid when I was 16," said Sabalenka.
"I think my first few games I was trying to adjust for her rhythm and her game, and then I kept trying to play my game, be aggressive and fight for every point."
The Australian Open champion will face Egyptian MayarSherif in the next round after she beat Elise Mertens 6-4, 0-6, 6-4 earlier Monday.
Sherif, 26, is the first Egyptian to reach a WTA 1000 quarter-final.
Two-time French Open winner Swiatek recovered from an early break by world number 17 Alexandrova to take the first set in what proved a trickier clash than it seemed on paper.
The Pole surrendered a 5-2 lead in the second and failed to convert a match point on the way to a tie-break, in which Alexandrova hit three aces to force a third set.
Swiatek broke for 2-1 and held on to that advantage before breaking to love to clinch victory in two hours and 27 minutes, finishing at past 1:00 am Tuesday morning.
"(Playing so late) wasn't easy for sure," said Swiatek.
"It's tough, you have to sleep in the middle of the day to be fresh in the evening."
Swiatek will face Croatian Petra Martic, who upset Czech player BarboraKrejcikova 6-3, 7-6 (7/1).
Third seed Jessica Pegula beat Italy's Martina Trevisan 6-3, 2-6, 6-3 and will face Veronika Kudermetova, who beat Daria Kasatkina in a tight all-Russian battle 7-5, 1-6, 7-2 (7/2).
Maria Sakkari beat home favourite Paula Badosa 6-4, 6-4 to set up a quarter-final clash with Romanian Irina-Camelia Begu.
In the men's competition second seed Medvedev, 27, edged out his friend Shevchenko 4-6, 6-1, 7-5 to reach the fourth round.
He will face Aslan Karatsev, who beat Alex de Minaur 6-3, 4-6, 6-4.
"When you win 7-5 in the third, it's always mentally a brutal match, so I'm happy that I managed to win it," said 2021 US Open winner Medvedev.
Argentine player Pedro Cachin, ranked 67th, took out world number 11 Tiafoe with a 6-1, 7-6 (7/2) victory and will face lucky loser Jan-Lennard Struff in the next round.
Stefanos Tsitsipas beat Sebastian Baez 7-5, 3-6, 6-3 to progress, after needing three sets against Dominic Thiem in the previous round too.
"I had to bring the best out of my game," said the Greek world number five, runner-up at the Australian Open.
Tsitsipas faces Bernabe Zapata Miralles in the last 16 after the Spaniard defeated Roman Safiullin 6-3, 3-6, 6-3.
Tiafoe's countryman, US baseliner Taylor Fritz, saw off Cristian Garin and will meet Zhang Zhizhen, who surprisingly ousted Briton Norrie.
The world number 13 fell in three sets, with Zhang winning two tie-breaks to triumph 2-6, 7-6 (7/2), 7-6 (7/2).