Lopez will be in a walking boot, and the Nets will update his status on March 23.
The 23-year-old suffered the injury in the third quarter of Sunday night's game in Charlotte and did not return. He underwent X-rays later that night, but the team did not reveal the news until Monday.
Lopez left the locker room in crutches, and coach Avery Johnson said he "badly rolled" his right ankle.
The news might have a negative impact on the Nets' pursuit of Dwight Howard by the March 15 trade deadline. Lopez had been prominently mentioned in trade talks involving the Magic center.
A league source said Lopez's injury not expected to have an effect on how Orlando proceeds.
Lopez had just returned from a broken right foot injury that caused him to miss 33 of the Nets' first 34 games.
Lopez is averaging 19.2 points and 3.6 rebounds in 27.2 minutes in five games.
Mike Mazzeo is a regular contributor to ESPNNewYork.com.