Tough tests await Djokovic, Federer

Kei Nishikori – Roland Garros Player Profile

World numbers one and two Novak Djokovic and Roger Federer remain on course to contest the US Open final on Sunday, but both players face a formidable challenge in Friday's semi-finals.

Top seed Djokovic will be looking to finish off an already successful season with a third grand slam title of the year when he faces defending champion Marin Cilic in the first men's semi-final.

Federer, a five-time champion at Flushing Meadows, takes on French Open champion and Swiss compatriot Stan Wawrinka in the second last four match.

Both semi-finals have the potential to be memorable and could prove to be a fitting build-up to Sunday's title match.

Djokovic, who had lost to Wawrinka in the final at Roland Garros, has never lost to Cilic in 13 previous meeting, including wins in the quarter-finals of the last two Wimbledon's. Despite Cilic's underdog status going into the match against his Serbian rival, he is quietly confident of chances of causing an upset.

"It's definitely the toughest matchup, I would say," said ninth seed Cilic.

"I haven't beaten him ever in my career. I had close matches the last few years, but I haven't found the right formula to be able to win a match."

Djokovic eased through the first three rounds of the tournament without dropping a set but found his next two matches – against Spaniards Roberto Bautista Agut and 18th seed Feliciano Lopez – harder going.

Lopez's big serve and accurate volleys proved a problem for Djokovic during two of the four sets of their match, a tactic Cilic is sure to employ against the Serb.

"He has a big serve," Djokovic said about Cilic. 

"The serve gets him out of trouble. I know him very well. I have played with him many, many times. We are great friends. Great guy.

"I'm sure he's gonna try to be aggressive, going to try to take his chances. That's how he won last year's US Open. I watched him play. He played great. Best tennis of his life."

Federer won five consecutive finals in New York City from 2004 but hasn't won the title there in the last seven years and last reached the final in 2009, when he lost in five sets to Juan Martin del Potro.

Nevertheless, Federer has been in sublime form on the North American swing so far and a lot of his success can be attributed to the effectiveness of his serve.

In his five matches so far at the tournament, Federer has saved nine of the 11 break points he has faced while averaging a massive 82 per cent first serve points won.

Whilst Federer hasn't lost a set in the tournament so far, he is well aware of the threat his countryman holds, having lost to him in the French Open quarter-finals this year.

"I'm looking forward to playing him because he definitely is a big test and a big challenge for me. He beat me in straight at the French Open, so I hope I can do better this time," the 17-time grand slam champion said.

Wawrinka credits that defeat of Federer at Roland Garros as the moment he realised he could compete with his illustrious compatriot on an even keel after Federer won 16 of their previous 18 matches in a rivalry dating back 11 years.

"I think the past three years I got closer to him. My level improved a lot. I'm playing better tennis," said 30-year-old Wawrinka.

"I think now we are both nervous when we enter the court. Before it was only me. I was nervous because I knew I wasn't at his level. And now I think we can see that he was also nervous … the past few years.

"That's a big difference because that shows how much he knows that I can play at his level."