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.

On the court, second-seeded Fernando Gonzalez knocked out Dudi Sela 6-3, 6-4 and No. 4-seeded Igor Andreev advanced with a 6-3, 6-4 win over Gael Monfils.

In other first-round matches Tuesday, Gianluca Naso, Philipp Petzschner and Korean Lee Hyung-taik all advanced.

Two first-round matches that were rained out Tuesday will open play Wednesday, which will also see the second round begin.