Capdeville tested Stepanek in the first set before falling 7-6 (7-2). Stepanek then took the second set handily, 6-1.
In other first-round action involving seeded players, sixth-seed Jurgen Melzer lost to Guillermo Garcia-Lopez 6-2, 6-7 (5-7), 7-6 (8-6), while eighth-seed Kristof Vliegen downed Victor Hanescu 6-4, 7-6 (7-4).
The event's winner will claim $68,800.
Boston schools pull out free condoms over wrapping complaints
Millions of Getty images now available for free via embed tool