World No.1 Novak Djokovic advanced to the second round of the US Open on Tuesday with a 6-1 6-2 6-2 victory over Lithuania's Ricardas Berankis.
Djokovic, seeking his seventh grand slam title and fourth trip in a row to the US Open final, fired 10 aces and 28 winners and needed only 82 minutes to put himself into a last-64 match-up against German Benjamin Becker, who eliminated Czech Lukas Rosol 6-3 3-6 6-3 6-4.
Roger Federer made a solid start to his bid for an 18th grand slam title, advancing to the second round by defeating Slovenia's Grega Zemlja 6-3 6-2 7-5.
The 32-year-old Swiss star and seventh seed booked a second-round meeting with Argentina's Carlos Berlocq.
"I felt great," Federer said. "Day session or night session, it doesn't really matter when you play on Arthur Ashe Court."
Federer, whose 56th grand slam start in a row matched Wayne Ferreira for the all-time record run, has only one title in his past 14 major starts - that coming last year at Wimbledon.
After a second-round exit at Wimbledon this year, Federer needed only 93 minutes to eliminate Zemlja despite surrendering a third-set break.
"You're going to have some hiccups like I had today. It was a minor one," Federer said. "I might have had more confidence if I had closed it out without that. This way I had to fight a bit more. Who knows? Maybe that gives me confidence too."
Federer, who won five US Open titles in a row from 2004-08, has not made the Flushing Meadows final since losing to Juan Martin del Potro in 2009.
This year, Federer is on a quarter-final collision course with second seed Rafael Nadal, whom he has never faced at the US Open.
Canadian 10th seed Milos Raonic fired 28 aces in beating Italy's Thomas Fabbiano 6-3 7-6 (8-6) 6-3, while John Isner blasted 16 aces to down Italy's Filippo Volandri 6-0 6-2 6-3.
Raonic is confident he can reach his first slam quarter-final from a section of the draw that features Spanish fourth seed David Ferrer and French No.8 Richard Gasquet.
Argentine qualifier Maximo Gonzalez upset Polish 14th seed Jerzy Janowicz 6-4 6-4 6-2 as the Wimbledon semi-finalist struggled with back pain and Bulgarian 25th seed Grigor Dimitrov, Maria Sharapova's boyfriend, lost to Portugal's Joao Sousa 3-6 6-3 6-4 5-7 6-2.
In the biggest upset of the opening two days, Australian Samantha Stosur crashed out with a shock three-set first-round loss to lowly ranked American qualifier Victoria Duval.
The 2011 champion gave up a one-set lead to lose 5-7 6-4 6-4 to the 17-year-old world No.296.
Stosur had appeared on track for a second-round meeting with veteran Slovak Daniela Hantuchova when she led by a set and 4-2, but collapsed to one of her worst defeats, undone by 56 unforced errors and 10 double faults.
Czech seventh seed Petra Kvitova, the 2011 Wimbledon winner, and 2009 US Open runner-up Caroline Wozniacki withstood challenges from tenacious Asian rivals to advance.
Kvitova, the top-ranked rival in Victoria Azarenka's quarter of the draw, fought off Japan's 92nd-ranked Misaki Doi 6-2 3-6 6-1, while Danish sixth seed Wozniacki dispatched 133rd-ranked Chinese qualifier Duan Ying-Ying 6-2 7-5.
Serbian 13th seed Ana Ivanovic, the 2008 French Open winner, beat Georgian Anna Tatishvili 6-2 6-0 and next faces Romanian Alexandra Dulgheru.
