Wales coach Gatland rings changes for Portugal encounter
Only winger Louis Rees Zammit and No. 8 Taulupe Faletau retain their spots as Gatland made wholesale changes from the team that edged Fiji 32-26 in their opening game.
"We've made a few changes this week given the six-day turnaround," said Gatland.
"This is an opportunity now for this match-day 23.
"I've said before, but there’s some great competition within the squad which is what we want to see.
"There's a chance now for this group to go out Saturday and to put down their own marker in the tournament.
"We've done a thorough debrief of last week's game and know the areas we need to improve.
"We have a clear plan of how we want to play on Saturday and it's about going out there and executing that as we have prepared."
Gatland added: "Portugal are a skilful side and will be raring to go this weekend in their first match of the tournament."
Dewi Lake, one of four players in the starting lineup making their Rugby World Cup debut this weekend, captains the side at hooker.
He missed the Fiji match because it was felt it came too quickly even though he had recovered from a knee injury he suffered in a warm-up match with England.
He is joined in the front row by Nicky Smith at loosehead prop and Dillon Lewis at tighthead prop.
Christ Tshiunza will make his international debut at lock alongside Exeter teammate Dafydd Jenkins, while Faletau packs down with Dan Lydiate and Tommy Reffell in the back row.
Lydiate, like full-back Leigh Halfpenny, is making his 10th World Cup appearance in his third tournament.
Halfpenny is joined in the back three by Rees Zammit and Rio Dyer, while Johnny Williams and Mason Grady line up in midfield, outside scrum-half Tomos Williams - who wins his 50th cap - and fly-half Gareth Anscombe.
Wales' replacements include Gareth Davies, Sam Costelow and Josh Adams as the backline cover.
Front rowers Ryan Elias, Corey Domachowski and Tomas Francis, lock Adam Beard and flanker Taine Basham provide cover for the forwards.
Wales (15-1)
Leigh Halfpenny; Louis Rees Zammit, Mason Grady, Johnny Williams, Rio Dyer; Gareth Anscombe, Tomos Williams; Taulupe Faletau, Tommy Reffell, Dan Lydiate; Dafydd Jenkins, Christ Tshiunza; Dillon Lewis, Dewi Lake (capt), Nicky Smith
Replacements: Ryan Elias, Corey Domachowski, Tomas Francis, Adam Beard, Taine Basham, Gareth Davies, Sam Costelow, Josh Adams
Coach: Warren Gatland (NZL)