Germany's Tommy Haas returns a shot to Serbia's Novak Djokovic in their men's singles fourth round match at the Sony Open tennis tournament in Key Biscayne, Florida, March 26, 2013. [Photo/Agencies]

Serbia's Novak Djokovic returns a shot to Germany's Tommy Haas in their men's singles fourth round match at the Sony Open tennis tournament in Key Biscayne, Florida, March 26, 2013. [Photo/Agencies]

Germany's Tommy Haas recorded the upset of the tournament when he stunned two-time defending champion Novak Djokovic 6-2 6-4 in the fourth round of the Sony Open at Miami on Tuesday.

Haas, who turns 35 next week, needed just 80 minutes to end Djokovic's 14-match winning streak at the tournament and consign the world number one Serb to just his second loss of the season.

"Playing against someone like Novak and coming out on top at this time of my career, it's unbelievable," Haas told reporters.

"These are the moments I appreciate the most, going on those big stadiums, big stages, playing against the best people in the world."

Haas's win was his second over a world number one, some 14 years after felling Andre Agassi in the quarterfinals of the 1999 Grand Slam Cup.

"All the credit to him. He played a great match and he was the better player, no question about it," said Djokovic, who won a third successive Australian Open title in January.

"As far as I'm concerned, it's definitely the worst match I have played in a long time."

The victory carried Haas into his first quarterfinal at Miami while improving his head-to-head record against Djokovic to 3-4.

The German next plays Gilles Simon after the 11th-seeded Frenchman rallied past another Serbian in Janko Tipsarevic, 5-7 6-2 6-2.

Djokovic's defeat opens the door for second seed Andy Murray, who eased into the last eight with a 6-2 6-4 win over Italy's Andreas Seppi, to replace Roger Federer as world number two should he win the Miami title.

Third seed David Ferrer also cruised into the quarters with a 6-4 6-2 win over Kei Nishikori.