Former champion and world number two Novak Djokovic was knocked out of the Sony Ericsson Open on Friday, falling 6-2, 6-7, 6-4 to Belgian Olivier Rochus in his opening match.
After two rain delays that forced organisers to reschedule some matches to Saturday, Rochus secured his biggest win since he beat then world number two Marat Safin at Wimbledon in 2002.
"He was motivated to win against somebody who's better ranked, top player," said Djokovic, who won the Miami title in 2007.
"He didn't have anything to lose."
The Serb committed 62 unforced errors and nearly lost his cool during the two hour, 55 minute second round match.
He slammed his racket during the opening game of the second set after Rochus came back from 0-40 down and after the match he left the court to jeers but still gave the crowd a thumbs up.
"I never expected to win," said Rochus, who won a Wimbledon juniors double title with Roger Federer in 1998.
"Novak, he has won a Masters Series five times; he won a grand slam, many things I have never did in my life. He is number two, so I think he has more experience than me."
Women's world number two Caroline Wozniacki also struggled through her opening match, but advanced by beating Bulgarian Tsvetana Pironkova 3-6, 6-3, 6-4.
Belgian Kim Clijsters, Serbian Jelena Jankovic, and champion Victoria Azarenka of Belarus also won in the women's draw.