Kei Nishikori retires to see Fernando Verdasco progress

Fernando Verdasco has booked his place in the semi-finals of the Barcelona Open after his opponent Kei Nishikori was forced to retire through injury.

World number 17 Verdasco had established a 4-2 advantage in the first set before Nishikori had to stop with the recurrence of a back problem.

The Spaniard will now face defending champion and fellow countryman Rafael Nadal for a place in the final.

The other semi-final is between Milos Raonic and David Ferrer.