Marin Cilic says his stunning US Open triumph is nothing less than a sporting miracle.

In one of the most unlikely finals in grand slam history, Cilic capped his stirring comeback from a controversial four-month exile from tennis with a 6-3 6-3 6-3 rout of Japanese trailblazer Kei Nishikori.

Incredibly, Cilic landed his maiden grand slam title – and Croatia’s first since his coach Goran Ivanisevic beat Pat Rafter as a Wimbledon wildcard in 2001 – a year after sitting out the New York major while serving a doping ban.

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The Court of Arbitration for Sport reduced the suspension from six months but the scandal still rankles Cilic, with the 25-year-old maintaining he tested positive for a prohibited stimulant contained in a supplement bought over the counter by one of his staff.

Even Roger Federer, a strong anti-doping advocate, said he believed Cilic had been guilty only of stupidity – not intentionally trying to cheat – after the big-serving Croat ended his hopes of a sixth Open victory with a crushing semi-final win on Saturday.

But Cilic said after Monday’s watershed win that the nightmare ordeal only fuelled his desire to hit back stronger than ever when his suspension ended.

Marin Cilic is the first Croatian grand slam champion since his coach Goran Ivanisevic won Wimbledon in 2001. Photo: Getty

He hired Ivanisevic during the ban and the pair started working – Cilic harder than ever before – during last year’s Open while the one-time world No.9 was in isolation.

Asked how he planned to celebrate his breakthrough win, Cilic said: ‘All over Manhattan. I hope it’s not going to be Hangover No.4’.

Cilic said the ban also made him mentally tougher, while Ivanisevic made playing tennis fun again.

“The most important thing that he brings to me is the joy in tennis,” Cilic said.

But despite all his hunger, determination and dreaming, Cilic never truly imagined he’d ever be a grand slam champion.

“This is just the peak of the world,” he said.

“I mean, these last three players or four players that I played against, I had a losing record.

“So even coming into any of those matches I was trying to win but not sort of knowing that I’m going to do it.

“Considering everything, I mean, it’s a miracle.”

Asked how he planned to celebrate his breakthrough win, Cilic said: “All over Manhattan. I hope it’s not going to be Hangover No.4.”

Hangover or not, Cilic will wake up with a record $US3 million ($A3.25 million) cheque and his ranking restored to No.9 in the world for the first time since 2010.

Next generation

Novak Djokovic, Rafael Nadal – who was unable to defend his title because of a wrist injury – and Federer continue to hold down the top three spots, but Cilic hopes his win serves as an inspiration to others on the “second line”.

With Stanislas Wawrinka also crashing the grand slam party at the Australian Open, before Nadal and Djokovic reigned at Roland Garros and Wimbledon, Cilic’s success means there have been four different men’s grand slam winners for two years in a row.

That was guaranteed after Cilic and Nishikori wiped out Federer and Djokovic in the semi-finals to ensure the final was the first grand slam decider not featuring any of the Big Three or Andy Murray since 2005.

The game of tennis is definitely going to evolve much more.

“A lot of guys are saying people would like to watch top four guys much more to extend their streak at the top and to extend their run at the grand slams because they attract the most, the fans and the TV, and everybody else,” Cilic said.

“But one day definitely they’re going to go out and there’s going to be a need for somebody else.

“I feel this time, this year, the guys from second line were a bit lucky because Andy Murray was also having trouble with his back, Wawrinka was up and down with his tennis after Australia, a few other players were not playing at the best all the time and Rafa is not here.

“So that opened a little bit the gate for everybody else.

“But I feel it’s going to definitely be much bigger competition from next year.

“I feel the guys at the top are going to pull the other guys, too. The game of tennis is definitely going to evolve much more.”

Nishikori beaten but unbowed

Workers at the Nissin Foods Company cheer on Nishikori in Tokyo. Photo: Getty

Japan’s Kei Nishikori won’t leave New York as the first Asian man with a grand slam title, but his near-miss has shown him what he’s capable of.

Chants of “Kei, Kei, Kei” rang out in Arthur Ashe Stadium as fans tried to lift him, but after dispatching three of the top five seeds in punishing encounters he was no match for Cilic’s power and precision.

“It’s a really good feeling,” he said of the support – which included the backing of the New York Yankees’ 25-year-old Japanese pitcher Masahiro Tanaka.

“Everybody calling me ‘Kei’ or “Nishi’,” said Nishikori, who said even though he has lived in Florida for a decade he often still finds Americans calling him “Key” or “Kay”.

That kind of mistake will be less frequent if Nishikori can continue to play as he has over the past fortnight.

His run to the final – itself a first for an Asian man – included wins over world No.1 Novak Djokovic, third-seeded Australian Open champion Stan Wawrinka and big-serving Canadian Milos Raonic, the fifth seed who was a Wimbledon semi-finalist.

His fourth-round win over Raonic took four hours and 19 minutes and ending at 2:26 on Tuesday morning, matching the latest finish in US Open history.

I don’t think a few years ago would happen like this. I think I showed my potential. I can beat anybody now

Then came a four-hour, 15-minute five-setter over Wawrinka and in his first grand slam semi-final he out-lasted Djokovic in four sets played in punishing heat and humidity.

“There is a lot of things, positive things, that I learned from these two weeks,” Nishikori said.

Perhaps most importantly for a player who has battled injuries throughout his career, knowing his body was up to the challenge was key.

“I played a long three matches, two five sets and another against Novak. My body is heavy, but I am able to play,” said the new world No.8.

“I don’t think a few years ago would happen like this. I think I showed my potential. I can beat anybody now.

“So if I can keep training hard, I think I have more chances coming up.

“Hopefully I can win next time and have something more.”