Rafael Nadal into Rio Open semi-finals after injury to Alexandr Dolgopolov

Rafael Nadal reached the Rio Open semi-finals without even having to walk out on court after his opponent Alexandr Dolgopolov withdrew injured from their last-eight tie.

Former world No 1 Nadal is playing at the clay court event in a bid to find some form ahead of a tilt at an unprecedented 10th French Open crown in June.

The 29-year-old has dropped to fifth in the world after an injury-hit 2015 and suffered a shock semi-final defeat to Dominic Thiem in the Argentina Open.

The Rio Open's official Twitter account revealed the news of Dolgopolov's injury on Friday.

"Dolgopolov was forced to withdraw due to injury. Dolgopolov injury: right shoulder," they tweeted.

Uruguay's Pablo Cuevas sealed a 6-4 7-6 win over Federico Delbonis of Argentina to set up a clash with Nadal in the last-four on Saturday.

But second seed David Ferrer failed to reach the semis as he was beaten 6-3 6-2 by the in-form Thiem.

The 22-year-old Austrian, who took the Argentina Open title last weekend, claimed four breaks from Ferrer to seal victory in 73 minutes.

"It was one of the best matches I've ever played, for sure," Thiem said. "I'm unbelievably happy to be able to maintain my form from Buenos Aires here in Rio."

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Thiem will next face world No 71 Guido Pella, who continued his fine run on the  Rio clay with a battling three set victory over Spain's Daniel Gimeno-Traver.

The Argentine fought back from losing the opening set 7-5, to take the second 6-1 before closing out the match with a 7-5 win in the third.