Federer of Switzerland thanks the crowd after defeating Monaco of Argentina following their match at the U.S. Open tennis tournament in New York. Picture - Reuters.

Roger Federer will face Jo-Wilfried Tsonga in the quarterfinals of the US Open, in a rematch of the Wimbledon quarters earlier this year, after he cruised to a straight-sets victory against Juan Monaco in the early hours of Tuesday.

Their match was delayed due to the preceding women's match in the court, and it wasn't until 23:50 local-time when the match began. However, the 30-year-old did his part and cruised past Monaco with a 6-1 6-2 6-0 in just 82 minutes.

The late start seemed to have no effect on him, as the five-time champion served out the first set in just 18 minutes, breaking twice in quick succession. He continued the form into the second set and asserted himself even more in the third when there was light rain in the air. At one point, the Swiss hit four successive aces and wrapped up proceedings by 01:13 in the morning.

Federer had restricted Monaco to just three games, and afterwards said that he was used to late starts.

You have to be ready, he said. I knew I was going to play late and there were all kinds of possibilities that they might move us to another court. As tennis players we're used to it.

It's tough for Juan. I've been in that position before when I lost badly on this court to Andre Agassi, so I know what it feels like.

Sometimes it's just not your day, but it was mine tonight and it feels great.

However, Federer will face a much bigger challenge in the quarterfinals when he faces 11th seed Jo-Wilfried Tsonga, against whom he lost at the same stage in Wimbledon earlier this year despite taking a two-set lead.  Tsonga came out on top against American eighth seed Mardy Fish 6-4 6-7 3-6 6-4 6-2 in grueling encounter to seal his berth in the quarters.

Earlier in the day, Novak Djokovic was given a torrid time by Ukrainian Alexandr Dolgopolov, but managed to come out victorious in a thrilling encounter. It ended 7-6 (16-14) 6-4 6-2 to Djokovic, and he will face fellow-Serb Janko Tipsarevic in the quarters after he defeated Spain's Juan Carlos Ferrero 7-5 6-7 (3-7) 7-5 6-2.

It was the world number one's 61st win in 63 matches this year, but he's had far easier encounters during the course of his dream-season.

At the Louis Armstrong Stadium, the 22nd seed Dolgopolov's caused the Serb problems aplenty with his sliced backhand and the first set was a real thriller. The two exchanged breaks of serve, and eventually, it went down to a tie-breaker.

Dolgopolov seemed to be in total control when he went 4-0 up but when the net cord gave Djokovic a helping hand, the Serb launched his comeback. After some real eye-popping tennis, the first seed took the set although he had to save four set points and saw five set points of his own saved.

The second and third sets were straightforward though, as Djokovic broke at the start of each to register a straight-sets win that which seemed doubtful during the 75 minutes of the first set.

Winning it was very important, Djokovic said of the tie-break afterwards. That was probably the turning point. After that it was a good performance.

He played a lot of low balls, slices - I was confused on the court. But it was really exciting.

Djokovic will next face his Davis Cup teammate Tipsarevic in the quarters.

It means there's going to be at least one Serbian in the semi-finals, which is great for our country, said Djokovic. I think this is the first time I play Janko in a Grand Slam. We are great friends. It's not going to be easy to play him, but look, it's the quarter-finals and we both want to win.

If both Djokovic and Federer get through their quarterfinal encounters, they will meet in the semifinals of the tournament.