Spaniard Rafael Nadal is out of the Miami Open after been forced to retire against Bosnian Damir Dzumhur.

The former world number one was expected to breeze through his second-round match and made a strong start on Saturday.

He claimed the first set 6-2 in just 44 minutes after Dzumhur made plenty of errors during the opening exchanges. The Bosnian made five double faults but was then handed the advantage soon after.

Nadal was pegged back in the second set and Dzumhur levelled with a 6-4 success, but the rising temperatures were making life difficult for both men.

The 14-time Grand Slam champion required medical treatment before retiring after 109 minutes on court, but is still hopeful it is nothing major.

Speaking after the match, the 29-year-old said: “Everything was fine until the end of the first set and I started to feel not very good. It was getting worse and worse and worse.

“I get a little bit scared to be too dizzy and to lose fluids. I called the doctor a couple of times. I decided I was not safe. I wanted to finish the match but I decided I would not.

“Hopefully it’s nothing. Hopefully it’s just the extreme conditions out there, the beginning of a virus combined with the conditions.”

Nadal will be hoping to get back to full fitness as he tries to find his form ahead of the French Open in May. He is currently priced at 5.00 to win the second Grand Slam tournament of the year with Dafabet.