DELRAY BEACH, Fla. — Qualifier Ryan Sweeting upset third-seeded Sam Querrey 7-6 (5), 6-4 in the second round of the Delray Beach International Tennis Championships on Wednesday.

DELRAY BEACH, Fla. — Qualifier Ryan Sweeting upset third-seeded Sam Querrey 7-6 (5), 6-4 in the second round of the Delray Beach International Tennis Championships on Wednesday.

The win over the 22nd-ranked Querrey — the highest ranked player the 118th-ranked Sweeting's beaten — puts him into his first career ATP Tour quarterfinal.

The top four seeds in Delray Beach were all Americans: Andy Roddick, Mardy Fish, Sam Querrey and John Isner; only Fish remains in the draw.

Sweeting will face Kei Nishikori in the quarterfinals. The 2008 Delray Beach champion secured a 6-3, 6-4 win over American James Blake.

Sixth-seeded Janko Tipsarevic needed six match points before he closed out a 6-2, 6-7 (8) 6-3 win over Blaz Kavcic of Slovenia.

Tipsarevic had one match point at 8-7 in the second set tiebreaker, but hit a return wide off of Kavcic's serve.

Kavcic, serving at 2-5 in the final set, saved three match points on his own service game before Tipsarevic finally took advantage of a second match point in the final game.

Qatar Ladies Open

At Doha, Qatar, top-ranked Caroline Wozniacki defeated 2006 champion Nadia Petrova of Russia 6-3, 6-2 to reach the quarterfinals of the Qatar Ladies Open.

The Dane joins No. 2 Vera Zvonareva and No. 5 Jelena Jankovic as the remaining seeded players in the tournament. Zvonareva downed Dominika Cibulkova of Slovakia 6-1, 6-2, and Jankovic defeated Sania Mirza of India 6-0, 6-1.

Wozniacki will play Flavia Pennetta of Italy, who earned a 4-6, 6-3, 6-4 win over Lucie Safarova of the Czech Republic.

Dubai Championships

At Dubai, United Arab Emirates, four-time champion Roger Federer and third-ranked Novak Djokovic reached the quarterfinals of the Dubai Championships.

Federer defeated Marcel Granollers of Spain 6-3, 6-4 in just over an hour, while Australian Open champion Djokovic overcame the net play of Feliciano Lopez of Spain 6-3, 2-6, 6-4.

Tomas Berdych reached the last eight after the third-seeded Czech beat Nikolay Davydenko 6-3, 7-6 (5).