Switzerland's Roger Federer cruised into the third round of the U.S. Open with a 6-4, 6-4, 6-4 victory over net-rushing Australian Sam Groth, but the No. 2 seed in the women's singles, Romania's Simona Halep, was stunned by a qualifier.

The second-seeded Federer lost his serve twice in Friday evening's match but he put constant pressure on Groth's service games and converted five of the 11 break points he created.

The world No. 3 played a clean match with 37 winners and just 20 unforced errors, compared to 38 and 30, respectively, off Groth's racquet.

He also was efficient with his net approaches, winning 18 of 27 points when he moved forward, whereas Groth, one of the few players on Tour that uses the serve-and-volley tactic, won just 26 of his 59 net points.

"What I like about these kind of matchups is there's always going to be something unusual that's going to happen, unusual shot-making. You have to react rather than just always play percentage tennis," Federer said afterward about his and his opponent's large number of forays to the net.

"You just hope to get the other odd ball back, and then all of a sudden it drops short; you've got to run up to it. Whenever somebody is at the net or you're at the net, there's always something of the unknown that's going to happen a little bit more."

Next up for Federer in the third round will be Spain's Marcel Granollers, who edged big-serving Croat Ivo Karlovic 7-6 (8-6), 6-7 (3-7), 7-6 (7-5), 3-6, 6-4.

In other second-round men's singles results Friday, Spanish No. 4 seed David Ferrer advanced when Australia's Bernard Tomic was forced to withdraw with a hip injury.

No. 6 seed Tomas Berdych of the Czech Republic continued to play inconsistent tennis but managed to outlast Slovakian Martin Klizan 6-3, 4-6, 6-2, 3-6, 6-3, while seventh-seeded Bulgarian Grigor Dimitrov routed Israel's Dudi Sela 6-1, 6-2, 6-2.

In third-round action in women's singles, Halep was stunned 7-6 (8-6), 6-2 by 32-year-old qualifier Mirjana Lucic-Baroni, a former teenage prodigy who reached the Wimbledon semifinals at age 17 but was off the WTA Tour for much of the past decade due to severe personal and financial problems stemming from an abusive father.

Russian No. 3 seed Maria Sharapova, however, advanced to the round of 16 with a comfortable 6-2, 6-4 victory Friday night over Germany's Sabine Lisicki. EFE