Former US Open champion Juan Martin del Potro on Saturday pulled out of the Australian Open as he continues to struggle with his recovery from knee surgery.

The 31-year-old Argentinian, who made the last eight at Melbourne Park in 2009 and 2012, has not played since slipping and hurting his knee on the grass in the Wimbledon tune-up at Queen’s in June.

“Our two-time quarter-finalist Juan Martin del Potro has withdrawn from AusOpen 2020 as he continues to recover from a knee injury,” the Australian Open tweeted.

“Wishing you all the best with your recovery. We hope to see you back in Australia soon.”

The injury-plagued Del Potro reached a career high of third in the world but has slipped down the rankings to 120.

The opening Grand Slam of the year gets under way on January 20.