Organizers of the Auckland Classic in New Zealand released a statement to say that the popular Argentine would miss both their tournament, which starts on January 2, and the Australian Open later that month.
"Juan Martin del Potro has confirmed he will withdraw from the Australasian swing due to fitness issues," the Classic organisers said.
Del Potro lit up the world of tennis in 2016 with a remarkable comeback which saw him take Olympic silver in the men's singles in Rio, before leading Argentina to its first Davis Cup title last month, beating Marin Cilic in a thrilling five-setter in the final in Zagreb.
He finished the season ranked 38th, including notable wins over Novak Djokovic, Rafael Nadal, Stan Wawrinka and No.1 Andy Murray, having started it outside the top 1,000.
A persistent wrist injury has stalled Del Potro's career, its highlight being victory in the 2009 US Open, beating Roger Federer in the final, sidelining him for much of the 2014 and 2015 seasons.
The 1.98m del Potro demonstrated he had returned to near his best form by pushing Murray all the way in a remarkable final at the Rio Games, then turning the tables on the Scot by beating him in the singles in the Davis Cup semifinals as Argentina knocked out holder Britain.
But the effort may have taken its toll and Auckland organizers said that Del Potro's management team had advised them that he had not had "sufficient recovery time" to take part in the early season events.
It is a blow for the Auckland tournament, which has Serena and Venus Williams among its line-up in the women's singles, but was billing del Potro as its star attraction in the men's singles.
In other tennis news Saturday, American Madison Keys confirmed she will miss the Australian Open with a minor wrist injury.
Keys finished 2016 ranked eighth but has had surgery on her left wrist since playing in the end of season WTA Championships and has not recovered in time for the Australian Open which starts on January 16.
"I will not be ready to play the 2017 Australian Open," Keys, 21, said in a Twitter posting.