Lewis features among three changes made to the starting line-up who beat Italy 36-3, making it three wins from four outings after their four-try 34-24 victory over Scotland, 14-13 win in Ireland and 26-18 defeat by England. Jamie Roberts (Cardiff / Blues Academy) comes in at full back and Alun Wyn Jones (Swansea / Ospreys Academy) is fit again to reclaim his second row place after being forced to miss the Italian match through an arm infection.
"This is the last match for the players to impress before we name the World Cup squad and, as we are up against France at the World Cup, there is a lot riding on this match," said Head Coach Chris Davey. "We are also playing Argentina and Georgia at the World Cup but it would be good if we could strike a psychological blow against France on Friday ahead of the tournament.
"France lost for the first time in the 2006 Championship last week when they were beaten by England but while I was pleased with our result against Italy and the fact that it means we have won three on the trot, this will be a tough test for us.
"There were a lot of pluses but perhaps we are not showing enough patience and we will probably need more variety against the French and change little bits of our approach."
Wales Under-21: Jamie Roberts (Cardiff/Blues Academy); Aled Brew (Neath/Ospreys Academy), Andrew Bishop (Ospreys), Tom Riley (Pontypridd/Blues Academy), Chris Czekaj (Cardiff Blues); David Flanigan (Pontypridd/Blues Academy), Martin Roberts (Neath/Ospreys Academy); Rhys Gill (Cardiff/Blues Academy), Duane Goodfield (Pontypridd/Blues Academy, captain), Phil Osborne (Newport), Alun Wyn Jones (Swansea/Ospreys Academy), Dominic Day (Carmarthen Quins/Scarlets Academy), Ben Lewis (Swansea/Ospreys Academy), Rhys Shellard (Pontypridd/Blues Academy), Adam Powell (Pontypridd/Blues Academy),
Replacements: Ed Shervington (Neath), Ian Jones (Llanelli/Llanelli Scarlets), Will Jones (Newport/Dragons Academy), Craig Everett (Worcester Academy), Tom Cheeseman (Bath Rugby), Liam Davies (Llanelli/Scarlets Academy), Aled Thomas (Newport/Dragons Academy).