(CNN) -- World number three Rafael Nadal of Spain survived a three-set battle to reach the quarterfinals of the Masters 1000 tournament at Indian Wells as second seed Novak Djokovic crashed out on Wednesday night.
Nadal is starting to recover his best form after his injury problems of last year, but the giant Isner posed a continuous threat when he leveled at one set it looked ominous.
But Spanish ace Nadal kept battling and got a lucky break in the fourth game of the decider as his U.S opponent's return hit the net cord and bounced back on his side of the net to fall down a break.
It gave Nadal a decisive break and he held on for victory in the fourth round match.
Nadal, who won the Indian Wells title last year and in 2007, is the lone survivor among former champions of the tournament:
Top seed Roger Federer of Switzerland went out to Marcos Baghdatis in the third round while Serbian ace Djokovic of Serbia joined him on the sidelines with a 7-5 6-3 defeat to Ivan Ljubicic of Croatia in their last 16 match.
27th-seeded Baghdatis could not repeat his heroics against Federer as he slipped to a 7-5 0-6 6-4 loss to Spanish 18th seed Tommy Robredo.
Home hopes were kept alive by Andy Roddick who advanced to the last eight with a 7-6 6-4 win over Austrian Jurgen Melzer, while fourth seed Andy Murray was detained on court for only 38 minutes as his fourth round opponent unseeded Spaniard Nicolas Almagro retired with a left ankle injury.
"He seemed like he was moving okay," Murray told the official ATP Tour Web site.
"At the start we had some pretty good points. But then it seemed like it came on pretty suddenly. He said he had done it yesterday, and if you have a bad ankle sprain, it's obviously very difficult to move."
Murray next plays Roland Garros finalist Robin Soderling, who reached the quarterfinals in California for the first time after beating ninth seed Jo-Wilfried Tsonga of France 6-3 6-4.