Kohlschreiber, seeded third, pulled out because of a respiratory infection. He was replaced by Julio Silva, who then defeated Matthias Bachinger 3-6, 6-2, 6-3 and advanced to the tournament round of 16.
Haas cited a nagging shoulder injury as his reason for withdrawing. His place in the draw hadn't yet been filled.
Two first-round matches that were rained out Tuesday will open play Wednesday, which will also see the second round begin.
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