Djokovic, who has only lost six games through three matches, clinched the win over his Serbian countryman Viktor Troicki with a backhand winner down the line.
Djokovic slam dunked his fellow Serb 6-0, 6-1 on centre court as he won his 15th match in a row and 17th dating back to late last year's Davis Cup where he won two singles matches.
"I am playing my best tennis of my life the last three months," Djokovic said. "It all started with my Davis Cup wins when Viktor was the hero."
Djokovic and Troicki had a short rest before heading off to one of the outer courts to play a quarter-final doubles match against Rohan Bopanna of India and Pakistan's Aisam-Ul-Haq Qureshi.
Djokovic said he always has mixed feelings about playing someone he knows so well.
"He (Viktor) is one of my best friends on and off the court. But one of us has to lose," said Djokovic who has a 8-1 record overall against Troicki.
Djokovic moves on to the round of eight in singles, where he will face the 18th-seeded Frenchman Richard Gasquet, who defeated eighth-seeded Andy Roddick of the United States 6-3, 7-6 (7/5).
Gasquet's win over Roddick is his second straight victory over a top 10 player. He beat Jurgen Melzner 1-6, 6-1, 6-4 in the previous round.
"It feels incredible for me to be in the quarter-finals here. I did well with my serve and my backhand, especially on match point," Gasquet said.
It was a frustrating loss for Roddick, who was runner-up in Indian Wells last year.
Roddick was warned by chair umpire Fergus Murphy after breaking a racquet in the second set. Then, in the tiebreaker, Roddick hurled his racquet across the court. He argued several times with Murphy and at one stage barked out "I am giving you a warning".
Asked why he got upset with Murphy, Roddick replied, "I only made one mistake. I broke one racquet and I feel it as a little presumptuous to give me a warning off one broken racket when he made a number of mistakes."
Former US Open champion Juan Martin del Potro survived five second-set points to defeat Philipp Kohlschreiber in their fourth round contest.
The 22-year-old Argentinian won the first set in a tiebreaker and looked to be headed for a third set when he fell behind 6-1 in the second tiebreaker but Kohlschreiber couldn't finish him off.
Del Potro dominated the rest of the tiebreaker, capping his victory with an ace to win at the WTA and ATP Masters event.
"Well, I think it is not normal to come back from 6-1 down in a tiebreak, but I got lucky and I took my opportunities, especially on my third match point with my serve," Del Potro said.
"I tried to make an ace and I did. Now I'm glad to go through to have the chance to play the quarter-finals here in this Masters. It is good for my future, too."
It was the 11th ace of the match for Del Potro, the 2009 US Open champion who has been one of the ATP's hottest players this year with a 17-4 record.
He moves on to play Spain's Tommy Robredo, who easily beat American Sam Querrey 6-1, 6-3 in the first contest of the day on the main stadium.
"Well, I know him," Del Potro said of Robredo. "He's playing really well. He beat Querrey easily today. Hopefully I will be better than today because I feel tired. But I will fight."
Djokovic crushes doubles partner to advance
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