League sources told ESPN and NFL Media that Robinson wasn't at practice Friday due to the knee ailment. Robinson suffered the injury during Thursday's practice while setting up in pass protection and his knee gave out, according to ESPN.
The Jaguars listed Robinson as doubtful for Sunday's season opener against the Kansas City Chiefs. The team will be down to their third-string left tackle, as backup Cedric Ogbuehi was ruled out with a hamstring injury.
Jacksonville plans on starting second-year offensive lineman Will Richardson against the Chiefs, according to ESPN. He was competing to be the team's starting guard but also practiced at left tackle in the preseason.
Robinson missed 14 games last season due to a torn ACL in his left knee. He underwent an MRI, but it remains unclear if the injury will be season-ending.