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.
Aaron Carter is still in love with Hilary Duff
NBC reportedly holds celebs hostage to Jimmy Fallon's show