World No. 7 Kei Nishikori breezed past Latvian lucky loser Ernests Gulbis 6-1, 6-4 on Thursday to reach the quarterfinals of the ABN AMRO World Tennis Tournament, an ATP 500 indoor hard-court stop in Rotterdam.

The top-seeded Japanese raced to a 5-0 lead in the first set, breaking twice and winning the first 14 points. Gulbis recovered his poise in the second set to be level at 3-3, after both had broken, before Nishikori did so again in the ninth game.

"I didn't really have any bad shots. I played much better than I did in the first match," said Nishikori, who came from a set down to beat Pierre-Hugues Herbert 3-6, 6-1, 6-4 in his opening match on Tuesday.

"I felt comfortable about my defensive shots and I'm getting used to the court," he said.

In a match that lasted 1 hour, 14 minutes at the Ahoy Arena, Nishikori won 70 percent of his first-serve points and 75 percent of his second-serve points. With his improved serve, he has won 10 of his last 11 matches.

Nishikori, who is seeking his second ATP Tour title of the season, will next face Hungarian Marton Fucsovics for the first time.

This is Nishikori's first event since a right-thigh injury forced him to retire in the quarterfinals of the Australian Open against Novak Djokovic.