Argentine second seed Juan Monaco booked his place in the semi-finals of the ATP Mercedes Cup following a routine 6-1 7-5 victory over Slovakian qualifier Pavol Cernevak.
Monaco, the world number 14, will next meet Spaniard Guillermo Garcia-Lopez, who eased past Dustin Brown 6-0 6-3.
The 28-year-old right-hander from Buenos Aires broke Cernevak's serve on three occasions in the opening set and then, having trailed 0-4 in the second, turned things around with four more breaks to advance in 96 minutes.
Monaco is chasing his third trophy of the season and seventh of his career after wins at Vina del Mar in Chile in January and then Houston in April, both on clay.
The other semi-final will be contested between top seed Janko Tipsarevic and Brazil's Tomaz Belluci after both men overcame German opposition in their respective last eight matches.
Tipsarevic came from a set down to defeat Bjorn Phau 6-7 (6/8) 7-6 (7/2) 6-4, while Belluci beat Cedrik-Marcel Stebe 6-4 6-1.