Updated

American Alex Bogomolov Jr. and Marin Cilic of Croatia advanced to the second round of the St. Petersburg Open on Tuesday, while defending champion Mikhail Kukushkin made an early exit.

Bogomolov defeated Igor Kunitsyn of Russia 6-3, 6-1, and Cilic ousted Ukrainian qualifier Sergei Bubka 6-4, 7-6 (1). Kukushkin was upset by Michael Berrer of Germany 6-1, 4-6, 6-4.

Bogomolov — who was making his debut at a second consecutive event in Russia after reaching the quarterfinals at the Kremlin Cup last week — broke Kunitsyn twice in the first set and three times in the second.

"I know Kunitsyn and the way he plays perfectly," Bogomolov said. "It was important to neutralize his backhand. So, I served hard and returned with maximum concentration."

Julien Benneteau of France also advanced with a straight-sets victory over Pere Riba of Spain, 6-2, 6-1.

The 22nd-ranked Cilic is looking for his first title of the season. Cilic broke in the ninth game of the first set but Bubka saved five break points in the 11th game of the second set. He won in a rout in the tiebreaker.

"It was really good for me to go through this match today," said Cilic, who reached the semifinals of the event four years ago. "Bubka was serving really good in some moments and especially in the second set. On 5-all I had five break points and he served three aces and one service winner, so, it was really tough."

Also, Dmitry Tursunov beat fellow Russian Teimuraz Gabashvili 7-5, 6-3. Serbian qualifier Dusan Lajovic advanced with a 6-4, 6-4 victory over Jeremy Chardy of France.