Former champion Novak Djokovic tumbled out of the Indian Wells ATP tournament on Wednesday, upset 7-5 6-3 by big-serving Croat Ivan Ljubicic in the fourth round.

While holder Rafa Nadal of Spain and fourth-seeded Briton Andy Murray both advanced, second seed Djokovic was eliminated in a match lasting one hour and 44 minutes.

The Serbian world number two, winner here in 2008, lost his serve in the sixth game of the second set and sent a forehand service return long to hand Ljubicic victory.

Ljubicic, the 20th seed, fired down 13 aces in the searing desert sunshine to record only his second win against Djokovic in seven meetings.

"I had a lot of opportunities and I didn't use many of them," Djokovic told reporters after converting only two of five break point chances. "My execution was very bad and he played well when he needed to."

Although the 6ft 4in (1.93m) Ljubicic lost serve in the third game of the match, he broke back in the eighth and 12th to take the opening set in just under an hour.

Repeatedly unleashing first serves above 130 mph, he swept through the second set to book a place in the quarter-finals against 21st seed Juan Monaco of Argentina, who beat Spaniard Guillermo Garcia-Lopez 3-6 6-2 6-1 earlier in the day.

"I served well," said Ljubicic, who climbed to a career-high third in the world rankings in 2006. "My serve helped me, especially in difficult moments.

FREE POINTS

"You can't beat Novak only with a serve, but it does help you a lot if you can get a lot of free points off that shot. I was striking the ball nicely, and I felt like I could control the points off the baseline."

Djokovic's early departure followed the premature exit on Tuesday of world number one and three-times champion Roger Federer, who suffered a shock defeat to Cypriot Marcos Baghdatis.

Nadal overcame towering American John Isner 7-5 3-6 6-3 and Murray advanced after Spaniard Nicolas Almagro retired hurt with a left ankle injury when trailing 6-2 1-0.

Twice champion Nadal, who beat Murray in last year's final, broke the six-foot-nine Isner in the fourth game of the third set before sealing victory with a forehand winner down the line.

The Spanish left-hander leaned backwards in delight to celebrate his advance to the last eight where he will play Czech Tomas Berdych, who crushed Serbia's Viktor Troicki 6-1 6-3.

"I am feeling really well and I am feeling good on court," said Nadal, who has shaken off the knee injury that forced him to abandon his Australian Open title defence in January.

Seventh-seeded American Andy Roddick needed just one break of serve to beat Austrian Juergen Melzer 7-6 6-4 in a tight match and will next meet Spaniard Tommy Robredo, who battled past Baghdatis 7-5 0-6 6-4.

Sixth seeded Swede Robin Soderling brushed aside Frenchman Jo-Wilfried Tsonga 6-3 6-4 and will face Murray in the last eight.