The top-seeded Wawrinka, a Gstaad finalist in 2005, was down a break in the third before rallying for the win over the No. 8-seed. Wawrinka, of St. Barthelmy, will face Romania's Victor Hanescu, who defeated French qualifier Jeremy Chardy 6-3, 7-6 (3).
In the other bracket, 88th-ranked Guillermo Garcia-Lopez of Spain upsted third-seeded Mikhail Youzhny of Russia, 4-6, 7-5, 6-3. Garcia-Lopez will meet No. 7 seed Igor Andreev of Russia, a 7-6 (4), 6-3 winner over Marin Cilic of Croatia.