Lee was injured after catching a 20-yard pass and getting hit low by safety Damontae Kazee, who was then flagged 15 yards for lowering his helmet to initiate contact. Kazee made contact with Lee's left knee, causing it to bend at an awkward angle.
Jaguars coach Doug Marrone had no update on Lee's injury after the game, saying a diagnosis isn't expected to come until Sunday.
"I'm waiting for the doctor to tell me so I can tell you guys, but I know what I see," Marrone told reporters. "I'm not going to sit there and say it didn't look bad. It looked bad."
Lee is considered one of the NFL top young wideouts. Last season, he caught 56 passes for 702 yards and three touchdowns.
If Lee misses any significant portion of time stretching into the regular season because of the injury, it'll be a big blow to the Jacksonville offense that was counting on his production for 2018. With Allen Robinson and Allen Hurns leaving in free agency, the Jaguars are counting of Lee to play a significant role in the Bortles-led passing attack.