Johnson (ribs) participated in limited fashion in Monday's practice, Scott Smith of the team's official site reports.
The undrafted rookie did not play in Saturday's preseason-opening win over the Bengals and is not yet able to participate in practices without restriction. Johnson had impressed teammates and coaches since arriving in May, but unless he can get on the field for at least one of the final two preseason games, it may be difficult for the Barton College product to even garner a practice-squad spot.