The Welsh youngsters lost to Scotland on Friday but are determined to bounce back with an impressive performance tomorrow.
Lewis said, "We always said every player would have a chance to start at least one game, or have a decent amount of game time, it's a case of rotating the squad and giving everyone an opportunity.
"We have looked at the footage of the Scotland game and have tried to highlight weaknesses in attack, while Shaun Edwards has had more of a chance to work on our defence ahead of tomorrow's game, which has been a positive experience for the boys.
"We were bitterly disappointed to lose on Friday especially after being 14 points ahead early in the second half. But we have a chance to put things right tomorrow and if we win we will play the winners of Georgia v Italy.
"Training has been going well and the players are gaining a lot from the experience of being together as a squad for an intense period."
Wales team v Portugal: Dafydd Howells (capt, Ospreys); Josh Adams (Scarlets), Garyn Smith (Blues), Tyler Morgan (Dragons), Rhys Williams (Exiles); Daniel Jones (Scarlets), Tom Williams (Blues); Keagan Bale (Dragons), Ryan Elias (Scarlets), Dillon Lewis (Blues), Gareth Allen (Dragons), Rory Thornton (Ospreys), Tom Phillips (Scarlets), Matthew Marley (Blues), Jonathon Fox (Ospreys)
Replacements: Robert Lewis (Blues), Torin Myhill (Scarlets), Alex Jeffries (Dragons), Adam Williams (Ospreys), Michael Snook (Blues), Oliver Griffiths (Dragons), Daniel Brooks (Ospreys), Luke Price (Ospreys), Joe Thomas (Ospreys), Ben Calder (Exiles), James Whittingham (Blues)