New England Patriots center Ted Karras suffered an MCL sprain in Sunday night's loss to the Houston Texans, NFL Media's Ian Rapoport reported.
Karras, 26, was scheduled to have an MRI on Monday to confirm the diagnosis.
"At first glance, the hope is that it's something he can return from," Rapoport tweeted.
Karras has started all 12 games this season in relief of incumbent starter David Andrews, who was placed on season-ending injured reserve before Week 1 with blood clots in his lungs. Entering Sunday's game, he had played 100 percent on the team's snaps.
The 2016 sixth-round draft pick has allowed just two sacks of Tom Brady and committed three penalties in 841 offensive snaps.
Karras was injured in the third quarter of the 28-22 loss in Houston and replaced by veteran backup James Ferentz.