"Becker is a quality opponent and he should have won the first set,'' Djokovic said. ``I was fortunate enough to come back and win the first set, and after that, I was much more comfortable on the court.''
Djokovic was playing in Arthur Ashe Stadium, where the wind often swirls to players' frustration.
"You need to have this adjustment, footwork, steps, in order to get on the ball,'' Djokovic said. "I didn't have that in the first set. I was still trying to find my way from baseline, and the other side he was serving well. ... After I played a good tiebreak, everything kind of settled. I started to serve better, started to step into the court, which is important.''
Murray was in Louis Armstrong Stadium, a place that had bedeviled him in the past. Last year, he was pushed to four tough sets in the third round and quarterfinals there.
Another Grand Slam winner, Li Na, also showed some championship form on Ashe. This time, her opponent, Laura Robson, looked very much like a teenager.
The fifth-seeded Li avenged her third-round upset loss to the young Brit at last year's U.S. Open, winning in straight sets at the same stage at Flushing Meadows.
Li came from a break down in the second set for a 6-2, 7-5 victory, crediting a pep talk from coach Carlos Rodriguez.
"After the talk I was feeling much, much better,'' she said. ``Because before I never try to share the feeling with the team.''
Australian Open semifinalist Sloane Stephens, seeded 15th, beat fellow American Jamie Hampton 6-1, 6-3.
Stephens' next opponent could be defending champ Serena Williams, who faces Yaroslava Shvedova in the nightcap at Ashe. It would be a rematch of their Australian Open quarterfinal, won by the young American.
Third-seeded Agnieszka Radwanska, No. 9-seeded Angelique Kerber and No. 9 Jelena Jankovic all advanced in straight sets.
Wimbledon runner-up Sabine Lisicki, seeded 16th, won't be making a run at Flushing Meadows after she was eliminated in straight sets by Ekaterina Makarova. The 24th-seeded Russian won 6-4, 7-5.
Fifth-seeded Tomas Berdych beat Denis Kudla of the U.S. 7-6 (3), 7-6 (3), 6-3. American Tim Smyczek, ranked 109th, reached the third round at a Grand Slam tournament for the first time. He edged 73rd-ranked Alex Bogomolov Jr. in five sets, needing nearly four hours to win 3-6, 7-6 (6), 2-6, 6-4, 6-4.
-AAP