The 19-year-old Nadal, a native of Spain and the top seed, now has a 34-match winning streak on clay. Thomas Muster of Austria holds the record with 40 straight victories on clay in 1995.
The left-hander, who is the reigning French Open champion, hasn't lost on the surface since early April. He has won eight events on it this year, is 49-2 overall on clay and earned $125,000 for the victory.
Gaudio, No. 3, won at Gstaad two weeks ago. He earned $66,000 as the runner-up.