NEW YORK — Marin Cilic was barred from last year’s U.S. Open during a doping suspension he still says was unjust.

Unable to compete, he watched the tournament on TV from his home in Croatia, while using the forced time away from the tour to improve under the tutelage of new coach Goran Ivanisevic.

Now, 12 months later, look at Cilic.

“Seems completely unreal,” he said, “to be called `Grand Slam champion.”’

The 14th-seeded Cilic won his first major final Monday, beating 10th-seeded Kei Nishikori of Japan 6-3, 6-3, 6-3 at the U.S. Open by using 17 aces and the rebuilt game and confidence instilled by Ivanisevic.

“This is a second chance he got,” Ivanisevic said, referring to Cilic’s four-month ban in 2013.

Cilic earned a $3 million winner’s check and will rise to No. 9 from his pre-U.S. Open ranking of No. 16, which made him the first man from outside the top 10 to win a Grand Slam title in a decade.

“This,” Cilic said, “is (from) all the hard work in these last several years — and especially this last year.”

He prevented Nishikori from becoming the first man from Asia to win a major singles championship.

“Tennis has not been our biggest sport in Japan,” Nishikori said.”

There hadn’t been a matchup between players making their Grand Slam final debuts at the U.S. Open since 1997.