Johnson suffered foot and hip injuries during Argyle's 1-1 home draw with Swansea on Tuesday and missed training on Thursday.
However, Argyle head coach Paul Mariner is not ruling the Benin international centre-half out of his Saturday plans.
Winger Alan Judge is set to be back in contention for Saturday's clash after missing out on Tuesday.
Mariner said: "Alan was a bit under the weather ahead and that sort of made my mind up about Tuesday."
Winger Craig Noone (knee) is also back in contention after missing the draw with Swansea but defender David McNamee (groin) is again ruled out by injury.