Ferrero will play Federico del Bonis of Argentina, who advanced to his first career semifinal on the tour by cruising past fellow qualifier Pavol Cervenak of Slovakia 6-1, 6-2.
Ferrero is playing in only his third tournament of the year after a long layoff caused by knee and wrist injuries. He was also a semifinalist in Stuttgart last year.
Pablo Andujar of Spain ended the run of wild card Cedrik-Marcel Stebe, easing past the German 6-2, 6-1 to earn a semifinal match against Lukasz Kubot of Poland. Stebe posted his first two wins on the tour to reach the quarterfinals.
Kubot outlasted Santiago Giraldo of Colombia 7-5, 5-7, 6-3.