"The gaffer's got a decision to make because we've got a good squad here," said Johnson.
"They (Purse and Loovens) have done well in the last two games, looked solid and kept two clean sheets.
"I don't know if it's me coming in and ruining things at the back, but I've played and we've conceded two goals.
"I'm a centre-half and I should stop goals, not go and score them. I can't argue if he (Dave Jones) drops me."
City will be without Trevor Sinclair after it was revelaled he will be out for upto a month with knee problems. Robbie Fowler is in raining as he recovers from a hip problem.
Will Dave Jones recall Jimmy Floyd Hasselbaink or give Steve MacLean and Steve Thompson another game together.
In my opinion it's time to give Tony Capaldi a rest at full back and get Kevin McNaughton back into the team. Capaldi was subbed after an hour at Hull and has been no better than average for several games now.
Cardiff v Charlton. Tuesday 4th December, ko 7:45pm.