(CNN) -- Juan Martin del Potro shocked world number one Rafael Nadal in the quarterfinals of the Masters 1000 tournament at Key Biscayne in Florida on Thursday.
Rafael Nadal was beaten 6-4 3-6 7-6 by Juan Martin del Potro.
The Argentine, who is seeded sixth in Miami, defeated the top seed 6-4 3-6 7-6 (7/3), in front of a raucous, pro-del Potro crowd.
Nadal had won all four of his previous meetings with del Potro without dropping a set, including a quarterfinal win at Indian Wells last month.
But Del Potro wiped all that from his mind, coming back from 0-3 down in the third set to prevail in a tiebreak.
The defeat means Nadal leaves Miami empty-handed again. He has never won the event, with runner-up finishes in 2005 and last year.
Del Potro will meet Andy Murray of Britain in the semifinals.
Murray beat eighth-seeded Spaniard Fernando Verdasco 6-1 6-2, avenging a fourth round defeat at the Australian Open earlier this year.
Murray can overtake Novak Djokovic for third spot in the world rankings with victory in the prestigious tournament in Miami.
Djokovic plays Roger Federer in the opening semifinal on Friday.