Johnson practised for the first time in two weeks on Wednesday, albeit on a limited basis, but he is pleased with the recovery.
"Good. We're doing everything from straight-forward running to moving laterally as well," Johnson told reporters.
"Things are going good. We're moving in a positive direction."
The Lions play the Atlanta Falcons at Wembley on Sunday, and Johnson revealed that a decision on whether or not he will play could be made as late as Sunday.