While Novak Djokovic, Rafael Nadal and Roger Federer still occupy the top three spots in the rankings, it is surely too early to say that today's US Open final represents a true changing of the guard.

Yet, when the Japanese Kei Nishikori takes on Marin Cilic, of Croatia, for the title here today, there will be a new grand slam champion, an intruder among the elite of the men's game.

It is the first time since the 2005 Australian Open that a grand slam men's singles final has not included at least one of Djokovic, Nadal and Federer. To get there, 10th seed Nishikori disposed of Milos Raonic, Stanislas Wawrinka and then, most impressively of all, Djokovic in the semi-finals to become the first Asian man to reach a grand slam singles final. Cilic, the 14th seed, beat Tomas Berdych and then demolished Federer in the semi-finals to reach his first grand slam final.

Although Nishikori has a huge following in Japan, there is a pretty good chance that both men could walk the New York streets without being recognised. It should not take away from the fact that each man's path to their first final has been a remarkable one. Nishikori almost did not play here after having a cyst removed from his right foot three weeks before the start, but came through back-to-back five-setters, both lasting more than four hours, and still had enough in the tank to beat world No.1 Djokovic.

This time last year, Cilic was sitting on the sidelines as he waited to hear the result of an appeal against a nine-month suspension after he failed a drugs test for taking a banned substance via a tainted supplement. The 25-year-old always said he had taken the substance without his knowledge but the road back to this point has been tough.

What the two men share is the fact that their resurgence has come after the arrival of a new coach, with Nishikori having hired Michael Chang, while Cilic called on Goran Ivanisevic when he first learned of the failed drugs test.

Chang and Ivanisevic - each won a single grand slam title - have instilled belief in their men and the results have been clear for everyone to see over the past fortnight.

"Nishikori looks like the evolution of Chang," Ivanisevic said, soon after Cilic's demolition of Federer. "It's great. You can see why he took Chang as a coach. First moment I heard Chang is a coach of Nishikori, I was like: 'this is a perfect match'.

"It's like, for me, Andy Murray and Ivan Lendl was a perfect match, same [type of] players. Looks like me and Marin are a great match, we are from the same country and this is working fine."

When Cilic was 14, he met Ivanisevic, who recommended him to Bob Brett, once Ivanisevic's coach and now the LTA's director of player development. Having been friends for a long time, Ivanisevic was perfectly placed to give Cilic the hard, honest truth. Which he did, immediately.

"Even three, four years ago, I told him, 'you have to play aggressive, you have to step up'. And then he went backwards; in the last three years he didn't improve," Ivanisevic said. "So I told him this has to change and it's very simple, 'are you going to go [forward]; are you going to take your chances; are you going to play aggressive? Because you are 1.98m and you can't run with Djokovic or Nadal; you have to use your weapons'.

"In Rome, we had this big talk and I told him: 'this is your time; now you have to step up; now you have to show me that you understand what I am telling you, that you believe in that game'.

"He's starting to believe. He started already in the French Open. I saw at Wimbledon he was believing, and now here this is really just paying off."

Nishikori leads Cilic 5-2 in their head-to-head meetings, having won both their matches this year, although they are level at 1-1 in their two previous US Open encounters.

Ivanisevic said Cilic would need to continue attacking if he is to beat the Japanese in the final. "He has to serve well, be aggressive," he said. "If Nishikori makes him run, again it's not good. It's important how he starts, because they're both going to be nervous, both are going to see their chance and it's going to be interesting."

Nishikori has always had plenty of flair but, prior to Chang's arrival, was inconsistent and let down by his body. Hard work off the court has left Nishikori physically stronger and he has added mental steel, reminiscent of Chang himself.

"I keep telling him after every match 'we are not done yet'," Chang said. "It is easy to be satisfied with what he has done so far, but here is an opportunity to win a grand slam. I will keep reminding him of that. He's beaten everyone and I have constantly reminded him of that. We have similar styles, so I have been able to advise him well with certain things."

Both men have enjoyed being back on the scene, able to pass on their wisdom to their player. One of their charges will become a grand slam champion today.