Ivo Karlovic of Croatia has withdrawn from the Olympics because of a foot injury, and he'll be replaced by Philipp Petzschner of Germany.
Petzschner will face Lukas Lacko of Slovakia in the first round. The change was announced shortly after Thursday's draw.
The 6-foot-10 Karlovic was considered a dangerous floater in the draw because of his dominating serve. It was not immediately announced which foot was injured.
Olympic tennis begins Saturday.