The defending champion and world number one lost in straight sets at the Sony Open to the German, while Serena Williams booked her semi-final place with a comfortable win over Li Na.
Novak Djokovic crashes out of Miami after shock defeat by veteran Tommy Haas
Novak Djokovic has crashed out of the Miami Masters in sensational fashion, losing in straight sets to the number 15 seed Tommy Haas.
Defending champ Djokovic lost for just the second time this season after never getting to grips with the German veteran to lose 6-2 6-4.
Haas, who kept the Serb off his game with a solid mixture of shots on a cool southern Florida evening, will now face Gilles Simon in the quarter finals after pulling off the biggest upset of the competition so far.
"There are days when you don't feel good on the court and this is one of those days," Djokovic said.
"All the credit to him. He was the better player. As far I am concerned it is the worst match I have played in a long time.
"I just didn't feel good on the court. The conditions were different. The balls didn't bounce at all and he used a variety of shots very well.
"I just didn't find a solution to come back into the match. I made so many unforced errors on the forehand side."
Haas, who turns 35 next week, seven forehand winners and won 76 percent of his first-serve points, ending the world number one's 14-match winning streak.
The German easily won the first set then clinched the victory on his second match point with a forehand winner to the open court, ending the one hour, 20 minute match on centre court.
Haas has won three of seven career meetings with Djokovic but this was his first win on the hardcourts.
Andy Murray, the highest seed left at Miami and who lost to Djokovic in last year's final, needed just 86 minutes beat Andreas Seppi 6-2 6-4 and book a quarter-finals slot against Marin Cilic, who overcame Jo-Wilfried Tsonga 7-5 7-5 (6/4)/
"Today I served well," Murray said. "You know, when I was down in games I served pretty good, too.
"That can change from day to day, but I just keep working on it each day. Focusing hard on each serve specifically."
Third seeded David Ferrer advanced to the quarter-finals with a 6-4, 6-2 victory over Japan's 13th-seeded Kei Nishikori.
Ferrer won 84 percent of his first-serve points and 5-of-9 break chances to eliminate Nishikori and book a last eight-date against Austria's Jurgen Melzer, who defeated Spain's Albert Ramos 2-6, 6-3, 6-3.
Richard Gasquet, the number eight seed, outlasted Nicolas Almagro 6-7 (3/7), 7-5, 7-6 (7/3) and will next face Tomas Berdych, who dispatched US 17th seed Sam Querrey 6-1, 6-1.
Women's world No. 1 Serena Williams reached the semi-finals with a straight-set victory over Li Na.
Breaking Li three times in each set, Williams fell behind in the second set before roaring back to hold off her Chinese opponent and wrap up the result in one hour and 50 minutes.
"It's good to be able to at least come back," Williams said.
"I like to believe that I try to be a solver. I just try to do things different if something is not working.
"She played such a good tie-breaker. It was important for me to win that."
Williams had three aces and six double faults to one ace and seven double faults for Li.
"I just can't hit any more double faults," Williams said. "It's embarrassing and unprofessional. I hit about 50 in one game and it was just outrageous. It was like at this point I shouldn't be a professional tennis player.
"That was my goal -- I'm not hitting any more double faults."
Williams improved to 7-1 against Li with her sixth victory in a row, Li's only win coming at Stuttgart in 2008.
"She has such fight," Williams said of Li. "She never quits and I think that we have a lot of that similar."
Li made a strong return to the tour at Miami after an ankle injury suffered in losing the Australian Open final, admitting that while her ankle felt "100 percent" she wished she could have served better against her top-ranked opponent.
"She's best player in the world," Li said. "If you couldn't hold, she never give you chance again. I still have to see the positive way. I played well so I should be try to be ready for clay court season."
Williams, trying to become the first six-time winner in Miami history, will face defending champion Agnieszka Radwanska, who beat Belgium's Kirsten Flipkens 4-6 6-4 6-2.
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