Former champs win at US Open

Defending champ Stosur wins in US Open 3rd round

Defending champion Novak Djokovic needed only 99 minutes to win and didn't face a single break point as he beat Rogerio Dutra Silva at the U.S. Open on Friday, breezing into the third round.

As Djokovic blasted past the Brazilian, two other former champions also advanced: Juan Martin del Potro and Lleyton Hewitt.

Del Potro downed Ryan Harrison of the United States, 6-2, 6-3, 2-6, 6-2, while Hewitt - who is playing on a wild card due to his low ranking - showed his trademark grit to outlast Gilles Muller of Luxembourg, 3-6, 7-6 (5), 6-7 (5), 7-5, 6-4.

Andy Roddick, another man to have won this tournament, was playing what could be the last match of his career, but sailed through with a 6-3, 6-4, 6-0 win over Australia's Bernard Tomic.

David Ferrer, the fourth seed, also progressed to round three by beating Igor Sijsling of the Netherlands, 6-2, 6-3, 7-6 (12).

Among the other leading men's seeds, Janko Tipsarevic comfortably beat Brian Baker of the United States, 6-4, 6-3, 6-4, while leading local hope John Isner suffered a rare tiebreaker loss but still defeated Finnish veteran Jarkko Nieminen, 6-3, 6-7 (5), 6-4, 6-3.

On the women's side, the main upset was Laura Robson beating China's Li Na, 6-4, 6-7 (5), 6-2. Having ended the career of Kim Clijsters in the previous round, Britain's Robson can make it a hat trick over former grand slam tournament winners when she faces defending champion Sam Stosur in the next round.

Top-seeded Victoria Azarenka of Belarus dropped only a single game for the second time in three matches, beating No. 28 Zheng Jie of China, 6-0, 6-1, to move to the fourth round.

Azarenka, who won the Australian Open to start the Grand Slam season, won 50 of the 77 points against Zheng, who has never been past the third round at Flushing Meadows.

So far, Azarenka has lost only six games in three matches over the first week.

Robson, meanwhile, get another challenge.

''I have had a fairly tough draw, haven't I?'' Robson said.

Ranked 89th, Robson had never been past the second round of a major tournament or knocked off a top 10 opponent before this year's Open.

''I have had lots of tough matches against some very experienced opponents, so the way that I see it, it was time to start winning a few of them,'' Robson said.

The seventh-seeded Stosur was pushed for the first time in this year's Open by No. 31 seed American Varvara Lepchenko, but the Australia dominated the second set for a 7-6 (5), 6-2 victory.

Stosur has never faced Robson - or really watched her play for long.

''She's full of confidence and had two very, very good wins,'' Stosur said.

Four-time major champ Maria Sharapova, the No. 3 seed, ended the surprise run of Mallory Burdette, needing 58 minutes to win, 6-1, 6-1. Fifth-seeded Petra Kvitova, the 2011 Wimbledon champ, also advanced with a 6-4, 6-4 win over France's Pauline Parmentier.