But X-rays have now ruled out a break although Johnson remains in discomfort and is likely to be sidelined for a fortnight.
And the casualty list is lengthening further at the City Ground.
Defender Danny Cullip's hamstring troubles have flared again, midfielder Gary Holt has sustained two broken ribs, Kris Commons a calf niggle and Paul Gerrard has a back injury while fellow goalkeeper Rune Pedersen has reported a hip problem.
But defender John Curtis is back on the training ground after recovering from an ankle problem.