Wright-Phillips handed in a transfer request over the weekend and played no part in Sunday's 1-1 FA Cup draw at Notts County.
However, with Johnson condemned to spend three months on the sidelines after suffering a serious ankle ligament injury in training on Thursday and the transfer window closing on Monday night, manager Roberto Mancini does not feel he has sufficient time to find a replacement if he allows Wright-Phillips to go.
"I can understand his position," said Mancini.
"We haven't had any offers for Wright-Phillips at this moment but is difficult for Shaun to join another team now.
"We still have another 24 hours, so anything can happen but it (Johnson injury) probably affects it."