* Djokovic sees off early challenge by Dimitrov
* Tsonga withstands fast start by Fish (Updates with Djokovic win, adds quotes)
INDIAN WELLS, California, March 12 (Reuters) - Australian Open champion Novak Djokovic survived an erratic start to beat Bulgaria's Grigor Dimitrov 7-6 6-1 in an error-strewn third round match at the BNP Paribas Open on Tuesday.
The top seed came from 2-5 down to win the opening set 7-4 on the tiebreak, then broke his opponent's serve in the second and sixth games of the second set to seal victory in just over an hour.
Dimitrov, at 21 the youngest player left in the draw, made four double faults when serving for the first set at 5-3 and his challenge then quickly folded.
Djokovic extended his winning streak to 20 matches since his last defeat, in October to big-serving American Sam Querrey in the second round of the ATP Masters 1000 event in Paris.
Intriguingly the pair will meet again in the last 16 at Indian Wells, Querrey having scraped past Australian Marinko Matosevic 7-6 6-7 7-5 earlier on Tuesday.
"I tried to hang in there and stay in the match," a relieved Djokovic said courtside after improving his record for the year to 15-0. "I started very bad, very poor.
"He served very well but he made four double faults at 5-3 and got me back into the match. He made a lot of unforced errors and I just had to get the ball back in the court."
Asked about the challenge of Querrey in the fourth round, Djokovic replied: "It will be very interesting. He won our last encounter in Paris a few months ago. He has a very big serve."
Earlier on Tuesday, eighth seed Jo-Wilfried Tsonga withstood a fast start by Mardy Fish to overcome the American 7-6 7-6 in a closely contested third-round match.
The big-serving Frenchman clinched the first set 7-4 on the tiebreak, then trailed 0-4 in the second as Fish raised his game in front of loud home support at the Indian Wells Tennis Garden.
Both players struggled to hold serve from the one end of the Stadium Court due to dazzling desert sunshine and Tsonga won the next four games to level the score.
However the Frenchman was then broken in the ninth after Fish, on the lunge, conjured a delicately angled backhand drop shot, before Tsonga immediately broke back in the 10th.
The Frenchman swept through the tiebreak 7-0 as the American made four unforced errors, wrapping up victory in just over two hours with a forehand crosscourt winner.
"I'm just happy to go through," a breathless Tsonga said courtside. "It's not very easy to play a match against an American here. I hope I will have more support in the next round.
"I was just a bit lucky in that first set and then he played very well for a couple of games, then I played better," added the Frenchman, who won his 10th ATP World Tour singles title in Marseille last month.
Tsonga booked his place in the last 16 for a fourth time in six appearances at Indian Wells and will next face Canadian Milos Raonic, who battled past Croatia's Marin Cilic 3-6 6-4 6-3 earlier in the day.
Later on Tuesday, British world number three Andy Murray was scheduled to face Lu Yen-Hsun of Taiwan in an evening match. (Reporting by Mark Lamport-Stokes; Editing by Frank Pingue)