Nadal retires from opening match at Miami Open

Spanish tennis ace Rafael Nadal retired from his opening match at the Miami Open against Bosnian Damir Dzumhur after suffering from apparent heat exhaustion.

Nadal easily won the first set 6-2 on Saturday but began struggling with physical problems amid the hot, muggy conditions and called for medical assistance on two occasions, the first time after losing the second set 4-6 and again while trailing 0-2 in the decider, reports Efe.

He was finally unable to continue, feeling "dizzy" in stifling conditions, falling to the 94th-ranked Dzumhur 2-6, 6-4, 3-0 after an hour and 50 minutes.

Nadal's exit comes a day after Swiss legend Roger Federer withdrew from this hard-court tournament prior to his scheduled opening match on Friday against Argentina's Juan Martin del Potro.

Del Potro lost to the Swiss World No.3's replacement, Argentine Horacio Zeballos, 4-6, 4-6.

Dzumhur also called for a doctor at the end of the first set of Saturday's second-round match and complained that he had been feeling dizzy and had stomach problems, but he was able to recover.

The 29-year-old Nadal, who struggled through his worst season in a decade last year, was unable to build on his momentum from last week's event in Indian Wells, California, where he reached the semi-finals before losing to Serbian World No.1 Novak Djokovic.