X-rays were negative, but Gallinari will undergo an MRI to determine the severity of the injury.
"It's worse than the one I had just two months ago," said Gallinari, who sat out six games in December due to an ankle injury. "It's worse than that one."
Gallinari left with the injury with 1:03 remaining in the third quarter after getting 12 points and seven rebounds in 28 minutes. That denied the Nuggets their leading scorer (19.7 points per game) and the NBA's fourth-ranked player in free throw attempts (8.2) down the stretch.
Nuggets coach Michael Malone lamented the absence of his "go-to player" but said, "Even without Gallo, we're up by nine with two minutes to go. ... We still had plenty of opportunities to win that game in regulation."
ESPN's Tim MacMahon contributed to this report.