World number one Brooks Koepka has withdrawn from the United States' Presidents Cup team due to a knee injury.
Koepka re-injured his left knee during the CJ Cup in South Korea in October and has been unable to regain fitness in time for the biennial contest at Royal Melbourne from December 12-15.
US captain Tiger Woods has selected Rickie Fowler to replace Koepka in his 12-man team.
Koepka said in a statement: "I notified captain Tiger Woods that despite constant medical care and rehab, I am not able to play golf at this time. I consider it to be a high honour to be part of the 2019 team and I regret not being able to compete.
"Since my injury in Korea I have been in constant contact with Tiger and assured him that I was making every effort to be 100 per cent in time for the Presidents Cup in Australia. However, I need more time to heal.
"I'm sorry I won't be able to represent the red, white and blue this time around and I wish my team-mates nothing but the best as they work to retain the Presidents Cup for the USA."
Woods added: "Brooks and I talked and he's disappointed that he won't be able to compete. I told him to get well soon and that we're sorry he won't be with us in Australia. He would clearly be an asset both on the course and in the team room."
Woods had previously stated that overlooking Fowler for a wild card was his "toughest call", the 15-time major winner picking himself, Tony Finau, Patrick Reed and Gary Woodland.
Fowler said: "These team events have been some of the most memorable weeks of my career. To be picked by Tiger to compete with him and the rest of the team is very special.
"It is impossible to replace the world's number one, but I can assure my team-mates and American golf fans that I will be prepared and ready to do my part to bring home the Presidents Cup."