NEW YORK - Marin Cilic hit all the right notes in a dominant 6-3 6-3 6-3 win over Kei Nishikori in the US Open final on Monday but it remains to be seen if the big Croatian is another one-slam wonder or perennial threat.

The final was a strange and unfamiliar one for tennis fans, the match marking the first time since the 2005 Australian Open that at least one of Novak Djokovic, Rafa Nadal and Roger Federer were not playing for the title.

At Flushing Meadows, fans had also been used to seeing one of the 'big four' walking away at the end of the fortnight with the silver trophy, Federer, Djokovic, Nadal and Andy Murray lifting every US Open title in the last decade except one.

Argentine Juan Martin Del Potro, who toppled Federer in five sets in 2009, was the only other man to clinch the title.

Since then Del Potro has not been back to a grand slam final.

Sitting in his post-match press conference with the trophy, even Cilic found it hard to believe.

"I mean, seems completely unreal to be called grand slam champion," said the 14th seed.

"It's just a huge accomplishment and huge moment for me."

Over the last few years fans having been watching intently for any signs of a changing of the guard at the top of men's game.

Until this year, Marat Safin - who clinched the 2005 Australian Open - and Del Potro were the only men outside the big four to have clinched a grand slam title in the last decade.

This year, however, two new names have been added to the honour roll as Swiss Stanislas Wawrinka created a shock by winning the Australian Open and Cilic claimed the US Open.