Olympic gold medallist Nicolas Massu pulled out of the Australian Open on Thursday after aggravating an ankle injury during his second round match against unseeded German Philip Kohlschreiber.

Kohlschreiber was leading the 18th seed 6-0, 2-0 when the Chilean pulled out.

Massu also retired from a match against Argentina's David Nalbandian during a warm-up event last week with the same injury.

He appeared to twist the same ankle again during the first set of his match against Kohlschreiber and required courtside treatment.

Massu continued with his ankle strapped but his mood darkened as the match wore on.

Later in the set, he angrily slammed his cap into a courtside chair with his racket and then threw the racket after it, risking a fine.

Massu won the singles and doubles titles at the Athens Olympics last year and was feted back home in Chile after earning the South American nation its first gold medals.

The withdrawal gifted Kohlschreiber a third-round berth against a French opponent in his first Australian Open appearance.

The 21-year-old will play either 14th seed Sebastien Grosjean or qualifier Jean-Rene Lisnard.