FLUSHING MEADOWS, N.Y. -- It was nearly midnight by the time Roger Federer took the court Monday.
And it wasn't too long before he walked off a winner.
Federer gave up only three games in a rout of Juan Monaco in Monday's fourth- round action at the U.S. Open. World No. 1 star Novak Djokovic also posted a victory, but American Mardy Fish was sent packing after losing in five sets to Frenchman Jo-Wilfried Tsonga.
Djokovic, the reigning Wimbledon and Australian Open champion, was tested mightily in the first set before steadying the ship to beat 22nd-seeded Ukrainian shot-maker Alexandr Dolgopolov 7-6 (16-14), 6-4, 6-2 on a blustery day at the USTA Billie Jean King National Tennis Center.
Djokovic needed a tiebreak to sneak out the opening set, and that's exactly what he did with an ultra-exciting 30-point extra session. Dolgopolov jumped out to a 4-0 lead in the tiebreak, but the Serb fought back to force a lengthy breaker.
After Djokovic claimed the 76-minute high-quality first set, Dolgopolov seemed to lose his desire to stun the No. 1 star. The Serb cruised over the final two sets to secure a fifth straight trip into the U.S. Open quarterfinals.
"It was an interesting first set," Djokovic said. "I think it was exciting for the crowd to watch because it was very close. But I think it was game-wise an ugly first set because I wasn't happy with the way I played."
Djokovic tallied a mere 13 winners on Day 8, but Dolgopolov piled up 44 unforced errors to help the Serb's cause. Djokovic also broke the Ukrainian's serve five times, compared to only two breaks for the loser.
Dolgopolov was a surprise Aussie Open quarterfinalist back in January.
The 24-year-old Djokovic is now an amazing 61-2 this year, including a whopping nine titles. The Serbian slugger was last year's U.S. Open runner-up to Rafael Nadal and lost to Federer in the 2007 final in Flushing.
Djokovic will meet good friend and fellow Serb Janko Tipsarevic in the quarters on Wednesday.
The third-seeded Federer and Monaco didn't start their match until about 11:50 p.m. (et) because of an extended women's fourth-rounder between top-seeded Caroline Wozniacki and Svetlana Kuznetsova.
It had the makings of an epic night, but Federer made quick work of the Argentine Monaco in a 6-1, 6-2, 6-0 decision.
He fired 14 aces in the 82-minute rout, ensuring the finish time didn't approach the record set in 1993, when Mats Wilander and Mikael Pernfors ended their five-set match at 2:26 a.m. Federer's dominance also ensured the match wouldn't be postponed by rain, which started to fall toward the end.
"I thought he fought bravely. Sometimes it's not your day. It was mine tonight," Federer said on-court after the victory. "I'm very happy with the way I played."
Federer showed flashes of the brilliance that has carried him to 16 major titles, including five U.S. Open championships from 2004-08. The former world No. 1 was also a runner-up in Flushing two years ago and was the runner-up at this year's French Open.
The Swiss' quarterfinal opponent will be the 11th-seeded Tsonga, who rallied to beat the eighth-seeded Fish, 6-4, 6-7 (5-7), 3-6, 6-4, 6-2. This is the first time Tsonga has reached the quarterfinals at the U.S. Open. His most successful Grand Slam result is the Australian Open, scene of his standout runner-up finish in 2008 against Djokovic.
Tsonga broke Fish's serve in the second game of the fifth set and held a 5-1 lead. Fish actually saved three match points before Tsonga, who had 59 unforced errors, finally capped the lengthy affair that delayed the night session with an overhand slam.
The 20th-seeded Tipsarevic reached his first-ever Grand Slam quarterfinal by holding off former world No. 1 Juan Carlos Ferrero in four sets, 7-5, 6-7 (3-7), 7-5, 6-2, at Armstrong Stadium.
"I'm really happy, but I'm more happy that my goal of being top 20 at the end of the year is happening, you know," Tipsarevic said. "I don't know my ranking. On Monday I know it's gonna improve even more."
Tipsarevic is competing in his 31st career major tournament.
The 31-year-old Ferrero was the French Open champion and U.S. Open runner-up back in 2003.
The 27-year-old Tipsarevic has never titled on the ATP World Tour.