George left Sunday's game with a concussion when Bennett slammed him to the ground during the fourth quarter.
With George out of the game, the Bills hung on for a 26-10 victory on the strength of four field goals by Scott Norwood.
"(George) is going to be a great quarterback," Bennett said. "I hate that we've got to face him twice a year."
Indianapolis traded Pro Bowl offensive tackle Chris Hinton, up-and-coming wide receiver Andre Rison and two first-round draft picks for the chance to select George with the first overall pick in the April draft.
George completed 13 of 24 passes for 160 yards and a touchdown against the Bills.
After he was hit by Bennett, George was sprawled on the Rich Stadium turf for about four minutes.
Colts' Coach Ron Meyer said George will be examined after 24 hours to make sure there are no residual effects, but added he expects the rookie to be back in the lineup for the Colts' home opener next week against the New England Patriots.
Kelly completed 28 of 37 passes for 283 yards, including a three-yard touchdown pass to Butch Rolle.
Thurman Thomas, last year's NFL leader in combined yards from scrimmage, ran for 84 yards and caught nine passes for another 61 yards. Thomas had a six-yard touchdown run with 1:37 remaining.
The Bills opened the game with a no-huddle offense and moved through the Colts defense to take a 3-0 lead on Norwood's 29-yard field goal.
George responded by moving the Colts 67 yards, with Dean Biasucci capping the drive with a 24-yard field goal.
The Bills, however, took control on Norwood's field goals of 31 and 37 yards and Kelly's three-yard touchdown pass to Rolle, putting Buffalo up, 16-3, at halftime.
Following the second-half kickoff, George moved the Colts 67 yards again, ending the drive with a 25-yard touchdown pass to Stanley Morgan.
Norwood's other field goal was a 47-yarder. He also missed twice from 44 yards.