Harris scored three points in nine minutes before exiting late in the first quarter with the injury. He didn't return to the game.
"The one thing I feel awful about is Gary Harris," Nuggets coach Mike Malone said afterward. "Definitely keep Gary in our thoughts.
"He's frustrated, just getting back from an injury, and to have that [and] not be able to come back in tonight. We'll see how severe the injury is, and hopefully we can get him back really soon.
"But Gary's such a big part of what we're trying to do. Big loss."
Harris, who didn't speak to reporters postgame, will get the imaging done in Orlando, where the Nuggets will head to face the Magic on Wednesday.
Harris just came back from missing a pair of games last week due to a sore left ankle Friday in Portland, where he scored 27 points in 36 minutes -- including a go-ahead 3-pointer with 16.5 seconds remaining -- to help Denver earn a 113-112 victory over the Trail Blazers.
Malik Beasley filled in for Harris down the stretch, finishing with 15 points in 28 minutes, including a critical 3-pointer late in the fourth quarter.