Alabama coach Nick Saban said Anderson is considered questionable for this coming week.
The No. 1-ranked Crimson Tide go on the road to No. 13 Florida next Saturday.
"We're checking out his knee," Saban said. "He's questionable as to what his circumstance will be here for the upcoming week."
Anderson, one of the top pass-rushers in college football, appeared to take a helmet to his knee when a Mercer player went to cut block him.
Anderson was looked at by trainers on the sideline and was then escorted to the locker room.
A preseason All-SEC selection, Anderson had a sack during Alabama's season-opening win over Miami.
He was third in SEC in sacks last season with seven, and third in tackles for loss with 10.5.
Saban said the injuries were relatively minor and that he expects them to return to practice next week.