Roger Federer
Roger Federer of Switzerland returns to Marin Cilic of Croatia during their match at the U.S. Open tennis tournament in New York. Picture - Reuters.

World number one Novak Djokovic and number three Roger Federer both progressed to the last-16 phase of the US Open after seeing off Nikolay Davydenko and Marin Cilic respectively at Flushing Meadows.

Djokovic continued his dream-season, ratcheting up his 60th win of the season with an untroubled 6-3 6-4 6-2 victory against Davydenko. The Serb will face 22nd seed Alexandr Dolgopolov next after the Ukrainian beat Ivo Karlovic 6-7 (4-7) 6-2 6-4 6-4.

It wasn't a spotless performance from the 24-year-old first seed, compared to some of his performances though the year, but he still had too much for the 39 ranked Davydenko, who fell short of expectations.

It's the first test I had in this tournament and it was expected, said Djokovic. I was aware of his qualities - Davydenko is a great player. He's been around for many years. He knows how to play on this stadium and he knows how to play majors.

In the earlier match, Roger Federer overcame a spirited Marin Cilic 6-3 4-6 6-4 6-2. In the crucial third set, the third seed broke at 4-4 before going on to cruise in the fourth.

The 30-year-old will meet Argentine Juan Monaco, who got past Germany's Tommy Haas 6-7 (3-7) 6-3 6-2 6-3, next.

Coming in I knew it was going to be tricky and I'm happy that I was able to counter his pace and his good play, said Federer. It was a tricky match, especially at one set all. At the beginning of the third set I thought that was a key moment because he had momentum on his side.

I was not returning and serving exactly the way I wanted, but I was able to turn it around and finished strong in the set. Then in the fourth things were a bit easier.