ST. PETERSBURG, Russia (AP) Mikhail Kukushkin reached the quarterfinals of the St. Petersburg Open on Tuesday, while Adrian Mannarino was eliminated in the second round.

Kukushkin, the St. Petersburg champion in 2010, recovered from 4-2 down in the first set to win 7-6 (2), 6-2 against 2017 champion Damir Dzumhur, who saved four match points before he was finally beaten.

The sixth-seeded Kukushkin will play either Karen Khachanov or Joao Sousa in the quarterfinals.

The seventh-seeded Mannarino was beaten 6-3, 6-1 in just over an hour by qualifier Egor Gerasimov, who last reached a tour-level quarterfinal in October 2018.

Norway's Casper Ruud came through a tough first-round encounter with Alexander Bublik 6-7 (3), 6-4, 6-2. The eighth-seeded Ruud plays Salvatore Caruso in the second round.

It was the first indoor win on the ATP tour for the 20-year-old Ruud, who is usually considered a clay-court specialist.