Schuettler has clinched one of the eight berths for the season-ending Tennis Masters Cup Houston and won consecutive titles earlier this month in Tokyo and Lyon. He was runner-up here two years ago to Marat Safin.
Fifth seed Mikhail Youzhny will be Schuettler's quarterfinal opponent he routed Yevgeny Kafelnikov, 6-2, 6-2.
Second seed Sebastien Grosjean moved into his second quarterfinal in as many weeks with a 6-2, 6-2 romp of Anthony Dupuis. He next plays Alex Corretja.
Trying to salvage an average season, third seed Gustavo Kuerten defeated Victor Hanescu, 7-6 (7-1), 7-6 (7-1). Once No. 1 in the world, Kuerten has never fully regained his form after hip surgery early last year.