Nadal into Rio semis

Rafael Nadal has progressed to the semis of the Rio Open after his quarter-final opponent Alexandr Dolgopolov withdrew with a shoulder injury.

The International Tennis Federation has rejected claims that Rafael Nadal failed a doping test. (AAP)

Rafael Nadal has advanced to the semi-finals of the Rio Open without hitting a shot.

The top seed moved on after his quarter-final opponent Alexandr Dolgopolov of Ukraine withdrew before the clay-court match with a shoulder injury.

Guido Pella of Argentina reached the semis beating Daniel Gimeno-Traver of Spain 5-7 6-1 7-5.

Pablo Cuevas of Uruguay was leading Federico Delbonis of Argentina 6-4, 2-4 when a downpour suspended their quarter-final.

Second seed David Ferrer was to face Dominic Thiem in a late quarter-final.