Marin Čilić blasted his way to a straight-sets victory over Kei Nishikori to win the U.S. Open final in less than two hours and claim his first Grand Slam title. In the surprise battle of the two first-time Major finalists, it was Čilić who handled the occasion by far the better and, as he had done against Roger Federer just two days earlier, restrained his opponent with an unrelenting combination of powerful, precise serving and pummeling ground strokes to win 6-3, 6-3, 6-3.

The 25-year-old 14th seed, whose only visit to a Grand Slam semifinal before this week had been at the Australian Open almost five years ago, had extraordinarily gone through the quarterfinal, semifinal and final without dropping a set. A player who once displayed a fragile mental state was nerveless and unmoved from his goal. Just 12 months on from being forced to watch the U.S. Open at home as he served a suspension for taking a banned stimulant, Čilić has come back stronger, mentally and physically, under the charge of fellow Croat Goran Ivanisevic and has now fulfilled his potential on the biggest stage to join his boyhood idol as a Grand Slam champion.

“I think this is all hard work in these last several years and especially this last year,” he told CBS’ Mary Carillo on court after the win. “My team has brought something special to me, especially Goran. We were working very hard. But the most important thing that he brought to me was enjoying tennis and always having fun. I think I enjoyed my best tennis over here and played the best tennis ever in my life.”

Nishikori, whose own substantial potential had been largely unfulfilled due to past physical fragility, but has gone up a level since the arrival of former French Open champion Michael Chang as coach, would have been a similarly storybook winner. Instead, the Japanese 24-year-old will have to contend with being the first Asian male to make a Grand Slam final. In contrast to his stunning upset win over Novak Djokovic, Nishikori this time looked cowed by the weight of the occasion. Likely, too, his heavy legs were down to a run of grueling victories -- five sets over first Milos Raonic and then Stan Wawrinka and then four sets in the sapping heat and humidity against the world No.1. There was the odd flicker of life, such as when he broke Čilić when he was serving for the set in the second and when holding break points in the third, but never any sustained form to halt Čilić’s march toward becoming the first player outside of men’s tennis famed Big Four to win a Grand Slam in five years.

“He was playing really well today, I couldn’t play my tennis,” conceded Nishikori. “It’s a really tough loss but I’m really happy for my first final. I want to thank my team, sorry I couldn’t get a trophy today, but for sure next time.”

More success should now await both men. After Stan Wawrinka became the first man outside tennis’ famed Big Four to win a Grand Slam title in over four years at the Australian Open in January, this was the first Major final not to feature one of Federer, Djokovic, Rafael Nadal or Andy Murray, in close to a decade. The belief is now clearly there that tennis’ big stages are no longer a closed shop.

However, there was predicable tension on show from both men in the opening stages. Nishikori had a break point on Čilić in the opening game of what was then a far from full Arthur Ashe Stadium. But Čilić would save that as part of a run of 19 of 20 points won on serve to claim the first set in 33 minutes. The only break came when Nishikori made three unforced errors at 2-3.

It was a similar story in the third game of the second set. While Nishikori saved a third breakpoint in the game with his best point of the match to date and a fine drop shot, Čilić was undeterred and got the breakthrough with more flat hitting that kept his opponent pinned back. A second break was forthcoming to allow Čilić to serve for the second set at 5-2, before, unsurprisingly, the magnitude of what awaited him began to show. Nishikori got a break back as a Čilić forehand sailed long. It could have been a turning point, but instead was just the most temporary of diversions in Čilić taking a two sets to love lead in the very next game.

Once again, in the third set, Čilić would claim the early break. With Čilić’s revamped serve continuing to be robotic-like perfection, Nishikori’s only hope was that his opponent would falter under the pressure as he closed in on a life-changing victory. And the man who has spent the past 10 years honing his craft in Florida had his chance. At 4-2, Nishikori had three break points, but a combination of Čilić’s power serving and errors from the 10th seed’s racket let them slip by. At deuce, the door was shut on hopes of a dramatic comeback when Čilić’s drop shot clipped the top of the net and bounced over, with Nishikori scooping his cross-court follow-up wide. Čilić faltered in serving a double fault on his first match point but this new, frighteningly mentally robust, Marin Čilić immediately regained his composure and fired a backhand winner to etch his name on the list of Grand Slam winners as one of the most unlikely in recent times.