Philipp Kohlschreiber of Germany has withdrawn from the Australian Open with a strained left hamstring.
The No. 21-seeded Kohlschreiber withdrew Tuesday morning before his scheduled first-round match against Slovenian Aljaz Bedene.
He was replaced in the draw by Frenchman Stephane Robert, a lucky loser from qualifying.
On the women's side, Polona Hercog of Slovenia also retired after losing the first game of her match against 25th-seeded Alize Cornet of France. A reason for her withdrawal was not immediately given.
Three players retired during men's matches on Monday, including No. 12-seeded Tommy Haas of Germany.