"He is here for a week for us to have a look at. He played at centre-back but he is not big enough to be a centre-back, I think he is a right-back," Plymouth assistant head coach John Carver told the Western Morning News.
"It is an open-minded thing. We will have a look and we will see what we think. The game was not a real test for him to be honest, but we will see what he is like with the rest of the players in three good days of training. We have to make sure he is good enough for us."
London-born Johnson was on the books at Chelsea before he linked up with Derby's Academy. He signed professional forms at Pride Park at the start of this season and has spent three months on loan at Stafford Rangers during the current campaign.