By Fitzgerald Cecilio

Defending champions Novak Djokovic of Serbia and Samantha Stosur of Australia keep their title-retention bid rolling, hurdling separate rivals Friday to make it to the next round of the US Open.

For the second straight match, Djokovic had an easy day of work, defeating clay-court specialist Rodrigo Dutra Silva 6-2, 6-1, 6-2 in just one hour and 39 minutes. He earlier defeated first-round rival Paolo Lorenzi in one hour and 13 minutes.

Djokovic fired six aces and just one double fault compared to Silva's three. The Serb only had 14 unforced errors compared to his rival's 36, making the match much easier for the reigning champion.

He will now face the winner between Frenchman Julien Benneteau and American Dennis Novikov in the third round.

Meanwhile, Stosur defeated American Varvara Lepchenko, 7-6 (5), 6-2, in the third round to advance against upset-minded Laura Robson, the British teen who eliminated Kim Clijsters in the second round and stunned ninth seed Li Na, 6-4, 6-7 (5), 6-2.

Stosur had a rocky start as she was broken by Lepchenko but immediately bounced back to tie the count at one. The two closely fought until Stosur won the final two points to end the first set in 59 minutes.

Stosur raced to a 5-1 lead before finally finishing the match in one hour and 28 minutes.

"I think as the match went on I probably became a little bit more comfortable, got used to her spin and maybe the wind a little bit more," Stosur said. "It was tricky out there during the first set, and when it's tight, you know, it's hard to really kick start something. I think once I got that first set then I may be relaxed a little bit more."

Stosur has never faced Robson during his career but she is expecting a tough fight with the 18-year-old British full of confidence after two big wins.

"Laura's obviously full of confidence and had two very, very good wins," Stosur said. "Definitely I can't go into that match lightly. I have to go out there and be on my game and ready to play some good tennis."

In other matches, third seed Maria Sharapova of Russia made it to the third round after defeating American Mallory Burdette, 6-1, 6-1, while 11th seed Marion Bartoli of France beat compatriot Kristina Mladenovic, 6-2, 6-4.

Fifth seed Petra Kvitova of Czech Republic also advanced to the third round with 6-4, 6-4 win over Pauline Parmentier of France, 6-4, 6-4.

In the men's division, world No. 5 David Ferrer of Spain eliminated Dutch Igor Sijsling, 6-2, 6-3, 7-6(12), to book a place in the third round against the winner of the Gilles Muller-Lleyton Hewitt encounter.

World No. 254 Steve Johnson continued his fairytale run at Flushing Meadows, ousting Latvia's Ernests Gulbis 6-7(3), 7-6(5), 6-3, 6-4 in three hours and 11 minutes. Next up for Johnson will be French No. 13 seed Richard Gasquet, who dismissed American Bradley Klahn, 6-3, 6-3, 6-1.


Defending Champs Djokovic, Stosur Hurdle US Open Foes