After a bruising 32-26 victory over Fiji in their group opener, Wales coach Warren Gatland has looked to his wider squad for the clash with Portugal, who were not in action in the opening round of games.
"Gareth gets an opportunity and in the past when he has started for Wales he has been excellent. He hasn’t had a lot of rugby, but he is looking sharp," Gatland told reporters on Thursday.
"2019 was obviously disappointing for him and he has had a few injuries since, but he is excited."
Only wing Louis Rees-Zammit and number eight Taulupe Faletau remain from the win over Fiji, with flyhalf Dan Biggar, fullback Liam Williams and lock Adam Beard all training separately this week as they nurse knocks from the physical encounter.
Leigh Halfpenny comes in at fullback, Tomos Williams takes over at scrumhalf and Dewi Lake will captain the team from hooker.
Christ Tshiunza will get a surprise run at lock alongside Dafydd Jenkins, the first time the former starts in the second row for Wales, while centres Johnny Williams and Mason Grady make their World Cup debuts in the midfield.
Rio Dyer is in the back three with Halfpenny and Rees-Zammit, while in the front row of the scrum, Lake has props Nicky Smith and Dillon Lewis either side of him.
Dan Lydiate and Tommy Reffell are the flankers alongside Faletau.
"This is an opportunity now for this matchday 23," Gatland said. "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 have a clear plan of how we want to play and it’s about going out there and executing that as we have prepared."
Portugal are not expected to provide much resistance to Wales, but Gatland warned against complacency.
"Portugal are a skilful side and will be raring to go this weekend in their first match of the tournament," he said.
Wales team: 15. Leigh Halfpenny, 14. Louis Rees Zammit, 13. Mason Grady, 12. Johnny William, 11. Rio Dyer, 10. Gareth Anscombe, 9. Tomos Williams, 1. Nicky Smith, 2. Dewi Lake, 3. Dillon Lewis, 4. Christ Tshiunza, 5. Dafydd Jenkins, 6. Dan Lydiate, 7. Tommy Reffell, 8. Taulupe Faletau
Replacements: 16. Ryan Elias, 17. Corey Domachowski, 18. Tomas Francis, 19. Adam Beard, 20. Taine Basham, 21. Gareth Davies, 22. Sam Costelow, 23. Josh Adams.
