Gstaad, Switzerland – Feliciano Lopez of Spain and Russian Mikhail Youzhny were among Friday's quarterfinal winners at the Swiss Open.
The fifth-seeded Lopez was leading Stanislas Wawrinka 6-4, 2-6, 4-3 when the second-seeded Swiss retired with a lower back injury.
Lopez will next face Dutchman Robin Haase, who outlasted 2011 Gstaad winner Marcel Granollers of Spain by a 5-7, 6-3, 7-6 (7-5) margin.
Youzhny, the No. 6 seed, rallied past fourth-seeded Juan Monaco of Argentina 5-7, 6-4, 7-6 (9-7). The Russian, who saved three match points, has reached his second semifinal here in three years.
Next up for Youzhny is 2008 champion Victor Hanescu, who beat German Daniel Brands 6-3, 6-4. Brands upset Roger Federer in Thursday's second-round action.