On the bench Dafydd Jones fills the berth vacated by Popham and Andy Williams is rewarded for his patience with a place on the bench covering the scrum-half position.
"Nothing has changed in our approach, we need to go out there and do what we do best, better than we have been doing it," said Johnson. "We have one of the best teams in world rugby coming to our shores.
"They have some great players and we have a huge regard for French rugby and their style of play. They will be formidable opponents and with the Championship at stake they will be making sure they go home with a victory.
"Our job is to make that task as hard as possible for them and nothing would give us greater pleasure than to be able to say we beat them and had a positive influence on the outcome of the tournament."
Johnson has endeavoured to maintain a consistent approach to selection as he names just his third team since taking over as caretaker head coach, but he admits the selection of Popham over Charvis was not forced upon him.
"Colin Charvis is an experienced player who offers a lot to this squad and we want to make sure we keep him around us this week, on Saturday and beyond," said Johnson. "But he has played a lot of rugby this season, the best part of twenty odd games already, missing just one match for Newcastle in the Premiership and featuring for us at international level throughout the campaign so far and in the Autumn.
"We are resting him, but he will remain part of the squad and we want him around to help lift the players. Alix deserves his chance to start and we have gone for Dafydd (Jones) on the bench for the energy and impact he will be able to offer.
"Andy Williams must be congratulated and he has been rewarded for his perseverance and professionalism. He has been around the squad for a while, doing much of the hard work as maybe third or fourth choice and he is finally getting his chance.
"Gareth Delve is unlucky to miss out, but Jonathan Thomas offers us cover across the back row and we also thought about giving Gavin Henson a start. We decided that would not be in the best interests of the kid and we are also trying to consolidate a centre partnership that has fired on occasions in Hal Luscombe and Matthew Watkins.
"Gavin's time will come again, but we have attempted to protect him a little on this occasion."