The two tight-heads that played in the Six Nations for Steve Tandy’s side will not feature this summer.
Sale-bound Tomas Francis was brought back into the international fold to shore up the scrum.
The 34-year-old is rested after his exertions with Provence as Wales try to get him through to the World Cup, while Bath’s Archie Griffin is absent after surgery.
Keiron Assiratti, the leading tight-head last autumn, withdrew from the squad after suffering a calf injury in Cardiff’s United Rugby Championship (URC) quarter-final defeat.
Lewis is joined in the squad by Sam Wainwright and Ben Warren, while Chris Coleman and Rhys Henry have helped in in training before the Baa-Baas fixture.
The three official members of the squad have a combined tally of just eight professional starts in 2025-26, but opportunity knocks.
“You always like to think you can add something to a team, so it has been a frustrating time for me,” said Lewis.
“The way the team finished the Six Nations was brilliant to watch. You could see a definite change and it was exciting, and something I was desperate to be a part of.”
After missing out twice, Lewis has worked for the first time under Tandy and his new scrum coach Paul James.
“You hear all the boys coming back into the clubs and speaking so highly of the environment and how much they enjoyed it,” said Lewis.
“It’s tough to listen to, but it also spurs you on to try to get back here, so I’ve loved being back in with a completely fresh, new coaching staff.
“Everything’s a bit different – there is a new outlook on the game and culture. I’ve loved it and it’s been nice to get back in.”