INDIAN WELLS, United States (AFP) — Reigning US Open champion Daniil Medvedev joined the growing list of top-seed casualties at the ATP/WTA Indian Wells on Wednesday, losing in the fourth round to world number 28 Grigor Dimitrov 4-6, 6-4, 6-3.

Medvedev, who won his first Grand Slam title last month at Flushing Meadows, had not lost a set heading into the fourth round but dropped eight-straight games, and had his serve broken six times against Dimitrov, en route to a stunning early exit for the top seed.

“I don’t remember myself losing three service games, even four service games ever on hard courts,” Medvedev said.

“That shows how slow this court is and the conditions, more like clay, which I don’t like. To lose four times the serve is just unacceptable. That’s why I lost the (second) set.”

The Bulgarian Dimitrov closed out the match on the first match point, when Medvedev blasted a forehand long.

“Been watching quite a bit of his matches,” Dimitrov said of Medvedev. “I really wanted to play this match to be completely honest. What he has been able to accomplish this past year and a half is pretty amazing. I think it really pushes me also to do better.”

Dimitrov will face Polish eighth seed Hubert Hurkacz, who rolled over Russian Aslan Karatsev 6-1, 6-3 on Wednesday in the quarter-finals.

In other men’s fourth-round matches on Wednesday, second seed Stefanos Tsitsipas defeated Australian Alex De Minaur 6-7 (3/7), 7-6 (7/3), 6-2 and third-seeded Alexander Zverev of Germany overpowered France’s Gael Monfils 6-1, 6-3 in just 61 minutes.

In the women’s draw, two-time winner Victoria Azarenka punched her ticket to the semi-finals with a straight-sets win — 6-4, 6-2 — over Jessica Pegula.

Azarenka, who is the only player left in the women’s and men’s fields to have won in Indian Wells, captured the title in 2012 and 2016.

The 32-year-old from Belarus needed 94 minutes to end the run of American Pegula and reach the final four of this event for the fourth time in her career.

“I really played well in the crucial moments,” Azarenka said. “I felt like I stepped up to the occasion a lot. That’s what I’m really happy with today.”

Azarenka will next face Jelena Ostapenko for a spot in the women’s final.