Leonardo Mayer of Argentina upset top-seeded Philipp Kohlschreiber 6-4, 7-6 (4) on Tuesday to reach the quarterfinals of the bet-at-home Cup.
Two-time champion Robin Haase started his title defense by defeating Guillaume Rufin of France 6-4, 7-6 (4) in the first round. The 68th-ranked Dutchman finished with 10 aces.
Haase, who won the event in 2011 and '12 and reached his third career final in Gstaad last weekend, will next play Daniel Brands. The German beat fifth-seeded Carlos Berlocq of Argentina 7-6 (4), 2-6, 6-2.
Victor Hanescu of Romania defeated Aljaz Bedene of Slovenia 6-2, 6-1, and Jan Hajek of Czech Republic beat Aldin Setkic of Bosnia 6-2, 6-1. Andreas Haider-Maurer beat fellow Austrian Dennis Novak 6-4, 6-4, and Guillermo Garcia-Lopez of Spain rallied to beat Thomaz Bellucci of Brazil 6-7 (1), 6-3, 7-6 (4).