Ljubicic was in complete control of the match. An early break in the first set was enough for the top-seeded Croatian, who did not allow any break points.

In the second, he quickly built a comfortable 4-0 lead before Wawrinka finally could hold his serve.

``All went just perfect today. I play better and better each match here. I love this slow surface, as it suits my game really well,'' Ljubicic said.

The defending champion will now play Dominik Hrbaty of Slovakia.

American Andy Roddick beat Austrian Jurgen Melzer 6-4, 6-3 to advance to the semis.

The third-seeded Roddick served 11 aces and nine service winners, compared to one ace for Melzer.

Roddick will next play Fernando Gonzalez, who beat second-seeded David Nalbandian 3-6, 6-3, 6-1.

The fifth-seeded Gonzalez, using an attacking topspin backhand, took control when he broke Nalbandian at love at 4-3 in the second set. He served out the set, saving two break points.

Gonzalez, who had lost five out of seven previous matches against Nalbandian, went up 4-0 in the third set. The Argentine showed little resistance and lost serve three times in the final set.

Hrbaty advanced to the semifinals after beating Austrian wildcard Stefan Koubek 6-1, 5-7, 6-2.