Johnson started Minnesota's first three games alongside Wallace and caught just six passes for 46 yards. He has missed the past two games because of a rib injury and watched while rookie Stefon Diggs caught 13 passes for 216 yards.
Diggs got the start in Sunday's 16-10 win over Kansas City at TCF Bank Stadium and hauled in seven catches for 129 yards. With Johnson close to returning, Zimmer wouldn't commit Monday to a starter moving forward.
"You don't lose your starting job because of injury, but you lose your starting job because of performance," Zimmer said. "But, no, I have not decided that yet."
Johnson was a pleasant surprise during the second half of last season, earning a starting job after being plucked off the Cleveland Browns' practice squad but hasn't looked like the same player this year.