Argentine Juan del Potro has withdrawn from next week's Brisbane International due to a persistent left wrist injury, tournament officials announced on Thursday.
The injury-ravaged 2009 US Open winner, who has not played since undergoing surgery last March, had hoped to return to competition in Brisbane in preparation for the Australian Open.
Del Potro is the second US Open champion to pull out of the Brisbane event in the past 48 hours following the withdrawal of Marin Cilic with a shoulder injury.
Croatia's Cilic won his first grand slam when he claimed the US Open title last year.
Del Potro's withdrawal comes less than three weeks before the first grand slam of the year starts in Melbourne on Jan. 19.
Despite losing two high-profile players, a strong field is expected for the event, including Roger Federer, Kei Nishikori, Milos Raonic and Grigor Dimitrov, who have all confirmed their participation.