Spain s Carlos Alcaraz (R) shakes hands with Germany s Alexander Zverev after their 2023 ATP Tour Madrid Open tennis tournament singles match at Caja Magica in Madrid on May 2, 2023. Photo: AFP
Third-ranked Daniil Medvedev crashed out against Russian compatriot Aslan Karatsev, 7-6 (7/1), 6-4.
In the women's competition world number two Aryna Sabalenka was forced to sweat by Mayar Sherif but eventually came through 2-6, 6-2, 6-1 to reach the semi-finals.
Top-seeded Spaniard Alcaraz, who also beat Zverev in last season's Madrid final, gained revenge for the German's triumph when they met later in the 2022 French Open quarter-finals.
Two-time Madrid winner Zverev, 26, was blown away in the opening set. He improved a little in the second but not sufficiently to trouble Alcaraz, who moved his opponent around at will.
"I played at a great level, I didn't let him dominate, I went on the attack the whole time, and above all, I returned really well," said Alcaraz, who won in one hour 22 minutes.
"I played a complete game, and that's how we have this result -- but it's not a normal result against (Zverev)."
Zverev zipped past Hugo Grenier 6-1, 6-0 in the third round, appearing to find form after the ankle injury he suffered last year, but was exposed by a razor sharp Alcaraz.
The US Open champion dropped just two points in the first set in his near-immaculate service games, and put strong pressure on the German's serve.
Alcaraz converted his third break point to take a 2-0 lead in the 11-minute second game, before wresting another from Zverev for 5-1, consolidating to take the set.
The duo traded blows on serve at the start of the second set before Alcaraz carved out a break for 3-2 when Zverev sent a forehand return wide.
Alcaraz again broke for a 5-2 lead with a neat forehand down the line and triumphed on serve when Zverev batted a return long.
Alcaraz, who turns 20 on Friday, is aiming for his 10th tour-level title after defending the Barcelona Open in April.
In the last eight, the Murcian will face Karen Khachanov who dispatched Andrey Rublev 7-6 (10/8), 6-4 in another all-Russian battle.
Medvedev, second seed in the Spanish capital, has admitted he struggles on clay and fell to another defeat against Karatsev on the dirt, as he did in Rome two seasons ago.
The 27-year-old secured an early break but Karatsev immediately struck back for 2-2.
They stayed on serve and Karatsev triumphed comfortably in the tie-break, his ball striking immaculate throughout the clash, hitting 28 winners to just four unforced errors.
Ranked 121st in the world, qualifier Karatsev broke the 2021 US Open winner for 3-2 in the second set and only dropped two points on his serve after that to progress.
"Feeling great, playing well, I just have to focus every match. I'll be preparing for the next round," said Karatsev.
(For more sports news and updates, follow Ahram Online Sports on Twitter at @AO_Sports and on Facebook at AhramOnlineSports.)