NEW YORK—Defending U.S. Open champion Marin Cilic said returning to Flushing Meadows is bringing back good memories and helping his form.

The Croat, who had never before reached a Grand Slam final, was a surprise champion a year ago but had a delayed start to this season because of a shoulder injury. In a second-round match that was his first on Arthur Ashe Stadium since he won the tournament, Cilic recalled the positive emotions he experienced.

"Somewhere around in the air, and I'm feeling that I'm close to finding them again and playing really good tennis," Cilic said after beating Evgeny Donskoy 6-2, 6-3, 7-5. "Showed even today that I was serving really well. When it counted I was making a lot of first serves in and really playing the attacking tennis that I was also playing last year. I feel these conditions out there on Arthur Ashe Stadium are bit quicker, the court is quicker, and that suits my game. So really enjoying it. Finding always the right way to play on these kind of courts is very important. So I feel I have the right path."

Nevertheless, Cilic acknowledged that he had nerves at the start of his title defense. "Well, I was bit nervous before the first round, and even the match in the first round I was a bit nervous, I have to say. That day was very hot and the ball is flying little bit, so when you are a bit tight, you know, it's tough to control the ball."

The 26-year-old has played better as the season has gone along, reaching the fourth round of the French Open and the quarterfinals of Wimbledon. However, he sees his current tennis as his best since coming back.

"I had pretty good Wimbledon, but over there I still felt that with my tennis it was a little bit up and down. But now I'm feeling that the way I'm hitting the ball, the way I'm moving on the court, the way I'm serving, it's really satisfying. So I'm really on a good way," he said.

The Croat plays Mikhail Kukushkin in the next round.