MIAMI (AFP) - World No. 1 Rafael Nadal and No. 2 Novak Djokovic advanced to the final of the Miami ATP Masters after both Kei Nishikori and Tomas Berdych pulled out of Friday's semi-finals.

The ATP Tour and Sony Open tournament officials said on their Twitter feeds that seventh-seeded Czech Berdych had withdrawn from his scheduled evening clash with top-seeded Nadal "due to gastroenteritis". Nishikori had earlier pulled out of his final-four meeting with Djokovic because of a groin injury.

It was a bizarre turn of events that wiped out the day's singles action but nevertheless produced a predictable pair of finalists in the tournament's top two seeds.

Berdych was at a loss to explain how he became so ill.

"Last night was basically the same as every other night. I ended up in the same restaurant, everything was fine," he said in comments the tournament posted on Twitter.

"I woke up at 7:30 in the morning with pain in my stomach. I am disappointed about not getting a chance to play," he added.

Nishikori withdrew after attempting to warm up for his early match against Djokovic, saying the left groin injury hindered his movement too much to allow him to play.

The injury ended Nishikori's sparkling run at the hardcourt tournament - where he saved four match points en route to a fourth-round victory over world number five David Ferrer and then vanquished Swiss great Roger Federer in the quarter-finals.

"For me it was my biggest tournament in a couple of years, to reach a semi-final of a Masters," a dejected Nishikori said in a hastily convened press conference. "It's really sad. I was really playing well."