"Disappointed to confirm that Nicolas Almagro has withdrawn from the #ausopen due to an ongoing shoulder injury. We wish him a fast recovery!" a post on the tournament's Twitter feed said.
Spain's number three player behind world number one Rafa Nadal and third-ranked David Ferrer, 28-year-old Almagro reached the quarter-finals at Melbourne Park last year.
(Reporting by Ian Ransom; Editing by Greg Stutchbury)