NEW YORK -- At this point in his career, Roger Federer recognizes the importance of a little extra work.
That's why the owner of a record 17 Grand Slam titles, and the man who spent more weeks ranked No. 1 than any other, was out there on a U.S. Open practice court late Tuesday afternoon, putting in some training time shortly after finishing off a 6-3, 6-2, 7-5 victory over 62nd-ranked Grega Zemlja of Slovenia in the first round.
At 32 and holding his lowest ranking, No. 7, in more than a decade, and coming off a stunningly early exit at the previous major tournament -- one of a series of newsworthy losses lately -- Federer is OK with making some concessions. He insists his passion for tennis is still there.
"I'm in a good spot right now," Federer said. "I want to enjoy it as long as it lasts."
As fan favorite Federer took the first step toward a possible quarterfinal meeting with nemesis Rafael Nadal, an unknown teen from the United States made a Grand Slam breakthrough Tuesday. Victoria Duval, a 17-year-old qualifier who is ranked 296th, pulled off quite an upset, eliminating 2011 U.S. Open champion Sam Stosur 5-7, 6-4, 6-4.
"A big moment, big stage. Not easy closing any match out, let alone a past U.S. Open champion," Duval said. "So happy I did it, though."
Duval jumped up and down with arms aloft after pounding a forehand winner to convert her fourth match point. And why not? Duval had never beaten a player ranked higher than 69th, never even faced one in the top 20, and never won a Grand Slam match.
"I know she didn't play her best today, and this is the best I've played in my career, so I'm really excited," Duval told the Louis Armstrong Stadium crowd. "I just tried to stay in the moment."
Stosur was unhappy with the way she played, including 10 double-faults and a total of 56 unforced errors, 21 more than Duval.
Former Stanford standout Mallory Burdette was beaten by No. 27 Svetlana Kuznetsova 6-3, 7-5.
No. 2 Victoria Azarenka, the 2012 U.S. Open runner-up and a two-time Australian Open winner, needed 10 minutes and six break points to take the first game against 99th-ranked Dinah Pfizenmaier, then dominated the rest of the way en route to a 6-0, 6-0 victory.
Her match came after top-seeded Novak Djokovic began his bid for a second U.S. Open title, and seventh major trophy overall, by beating 112th-ranked Ricardas Berankis of Lithuania 6-1, 6-2, 6-2.
"I played every point like it's a match point," said Djokovic, who recently added former top-10 player Wojtek Fibak as a coaching consultant.
Other straight-set winners included No. 5 Tomas Berdych and No. 10 Milos Raonic.
On a day that American men went 5-2, led by No. 13 John Isner and No. 26 Sam Querrey, a handful of seeded players made quick departures. No. 14 Jerzy Janowicz of Poland, a semifinalist at Wimbledon last month, was the most surprising to go, although he was treated by a trainer for a painful back during a 6-4, 6-4, 6-2 loss to 247th-ranked qualifier Maximo Gonzalez of Argentina.