Coach Mike Tomlin said Johnson "hurt his knee" on the final play of Sunday's 26-17 loss to the Raiders and "is being evaluated," Teresa Varley of the Steelers' official site reports.
Johnson made his ninth and final catch for 11 yards when he sustained the injury. According to Field Yates of ESPN, Johnson needed assistance from two teammates to get off the field, so his status should be watched closely in the coming days as the Steelers get more clarity on the nature of the issue. If Johnson is sidelined for any length of time, James Washington figures to move up the depth chart and join Chase Claypool and JuJu Smith-Schuster as Pittsburgh's top three wide receivers.