Djokovic advances at Key Biscayne

THE ASSOCIATED PRESS

KEY BISCAYNE, Fla. -- Novak Djokovic keeps winning easily at the Sony Ericsson Open.

The Serb reached the quarter-finals by beating 21st-seeded Tomas Berdych 6-3, 6-2 Tuesday. Djokovic, seeded third, has swept every set while losing only 15 games in three matches.

The winning streak comes after a match Djokovic described as one of the worst in his career -- a quarter-final drubbing against Andy Roddick at Indian Wells 10 days ago.

Djokovic broke serve five times against Berdych, who lost 15 of 24 points on his second serve.

"I knew he's very aggressive, but not really consistent from the baseline," Djokovic said. "He makes a lot of unforced errors, especially from the forehand side, so I changed the pace and I played really good tennis today."

Djokovic is seeking his second title at Key Biscayne. He won the tournament in 2007, then lost his opening match last year.

No. 8-seeded Svetlana Kuznetsova outlasted 18-year-old Caroline Wozniacki in the first women's quarter-final, 6-4, 6-7 (5), 6-1. When the two-hour 54-minute match in humid, 27-C sunshine ended, Kuznetsova slowly crumpled to the court in exhaustion.

The 2006 champion will play in the semifinals Thursday against the winner of the match Tuesday night between No. 11 Victoria Azarenka and Samantha Stosur.

In other men's fourth-round matches, fourth-seeded Andy Murray routed Viktor Troicki 6-1, 6-0, and No. 10 Jo-Wilfried Tsonga won 6-7 (4), 6-3, 6-2 against No. 7 Gilles Simon, the highest-seeded man to be eliminated.

Roddick, top-ranked Rafael Nadal and Roger Federer had matches scheduled later in the day.