NUR-SULTAN, Kazakhstan — Three of the top four seeded players lost their opening matches at the Astana Open, including top-seeded Aslan Karatsev.

Karatsev, who reached the Australian Open semifinals this year, lost to Finnish player Emil Ruusuvuori 7-6 (6), 6-4. Third-seeded Dusan Lajovic and fourth-seeded Filip Krajinovic also lost.

Ruusuvuori, who reached his first tour semifinal last year at the Astana Open, will next face eighth-seeded Ilya Ivashka in the quarterfinals.

Karatsev’s season has tailed off since his run at the Australian Open and winning a title in Dubai. The Russian hasn’t won more than two consecutive singles matches since reaching the final at the Serbia Open in April. He had a first-round bye at the Astana Open and entered the tournament in the second round.

Lajovic was eliminated by South Korean opponent Kwon Soon-woo 7-5, 6-4. Kwon will next face seventh-seeded Laslo Djere.

Another seeded player was knocked out when James Duckworth beat Krajinovic 7-6 (2), 6-3 in their second-round match. That sets up an all-Australian quarterfinals match between Duckworth and defending champion John Millman.

Alexander Bublik is the highest-ranked player remaining after he beat Miomir Kecmanovic 2-6, 6-3, 7-5. The second-seeded player from Kazakhstan next faces Carlos Taberner, who beat Egor Gerasimov 5-7, 7-6 (5), 7-5.