Novak Djokovic fell behind in the first set, yet still advanced to the fourth round at Indian Wells.
Mark J. Terrill/AP

INDIAN WELLS, Calif. (AP) - 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 ankle problem, routing Urszula Radwanska 6-3, 6-1 for her 17th straight win.

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.''

Djokovic moves on to play Sam Querrey, a 7-6 (5), 6-7 (7), 7-5 winner over Marinko Matosevic.

Djokovic hasn't lost since Oct. 31, when Querrey beat him at the indoors Paris Masters.

"He does everything really well: unbelievable forehand, unbelievable backhand, moves around the court great, returns great. It's tough to pick on something,'' Querrey said. "I might have to go outside of my comfort zone a little bit and do things I don't like to do, and hopefully it will pay off for me.''

Querrey is poised to take over as the top-ranked American in the men's game - albeit not in the top 10 - from Mardy Fish, who lost 7-6 (4), 7-6 (0) to No. 8 seed Jo-Wilfried Tsonga.

"The most important thing is your world ranking,'' Querrey said. "If you're top 10 I think you're seen a little differently.''

Azarenka was clearly bothered by her ankle, wincing after shots. She also has a stuffy nose.

"I could overcome those things and manage to take these chances in the important moments and really go for my shots, to make that happen, not to wait for her mistake,'' she said. "Because at some point I was waiting for her mistake, and I can't do that. She wasn't missing because she's a very, very consistent player, so I decided to just take everything in my own hands and see where it takes me.''

In other men's matches, 19th-seeded Tommy Haas got by No. 11 Nicolas Almagro 6-3, 6-7 (2), 7-6 (2), and Carlos Berlocq defeated No. 16 Kei Nishikori 6-2, 6-2.

On the women's side, fifth-seeded Petra Kvitova beat No. 19 seed Klara Zakopalova 6-2, 6-3, and sixth-seeded Sara Errani defeated No. 9 Marion Bartoli 6-3, 6-2. Errani next faces Maria Sharapova.

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