INDIAN WELLS, Calif. — Top-ranked Novak Djokovic reached the fourth round at the BNP Paribas Open on Tuesday when he beat Grigor Dimitrov 7-6 (4), 6-1 for his 20th consecutive victory.

Defending women’s champion Victoria Azarenka extended her own streak despite a nagging right ankle problem, routing Urszula Radwanska 6-3, 6-1 for her 17th straight win. Urszula’s sister, third-seeded Agnieszka Radwanska, was beaten by No. 13 Maria Kirilenko, 6-1, 4-6, 7-5.

No. 3 Andy Murray beat Yen-hsun Lu of Taiwan 6-3, 6-2.

No. 8 Caroline Wozniacki defeated No. 10 Nadia Petrova 7-6 (3), 6-3 to set up a quarterfinal against Azarenka that matches former top-ranked players against each other.

Djokovic trailed 5-3 in the first set when the 21-year-old Bulgarian committed six double-faults, including four in one game, to help the Serb force the tiebreaker. Djokovic won it on a backhand error by the youngest player remaining in the draw.

“It was not really a beautiful match to watch,” Djokovic said. “There were a lot of unforced errors, and we both look quite sluggish on the court.”

Dimitrov was broken twice in the second set while falling to 1-17 against top-10 opponents.

“He did all the work making winners and making unforced errors,” Djokovic said. “I just needed to hang in there and try to be patient.”