Nikolay Davydenko of Russia edged fourth-seeded Stanislas Wawrinka of Switzerland, 7-6 (7), 7-6 (3), in the Swiss Indoors first round on Tuesday.
The 31-year-old Davydenko, ranked 42nd, saved Wawrinka's five break point chances in the second set that went with serve.
Wawrinka, ranked 17th, faltered in the tiebreaker, dropping three points on serve.
Sixth-seeded Mikhail Youzhny of Russia eased past Bernard Tomic of Australia, 6-0, 6-2.
In other first-round matches: Brian Baker of the United States beat Radek Stepanek of the Czech Republic 2-6, 7-6 (5), 6-3; Matthew Ebden of Australia beat Victor Hanescu of Romania 6-3, 7-6 (3); and Swiss Marco Chiudinelli topped Guillermo Garcia-Lopez of Spain 5-7, 6-3, 6-4.