Anscombe starred in the 40-6 victory over Australia when he took over from Biggar, who has an arm injury and faces a race against time to be fit for Wales’ quarter-final, with Gatland’s side having already booked their place in the knockout rounds.
Biggar trained on his own on Monday, away from the main squad, as he steps up his recovery. Scrum-half Gareth Davies was also missing but is managing his workload and not a doubt for the weekend, where he will be on the bench.
Anscombe's 23 points against the Wallabies equalled Biggar's record for Wales at a World Cup and came after he spent a lengthy period on the sidelines with injury in the build-up to the tournament and missed all his side's warm-up games.
"He was great," Wales attack coach Alex King told reporters. "Just shows how things happen in the game. Guys who aren’t in the 23, things can happen and you have to step in at any moment."
Hooker Dewi Lake will captain the team with props Gareth Thomas and Tomas Francis on either side of him. The second row is made up of Will Rowlands and Dafydd Jenkins. Number eight Taulupe Faletau forms a loose trio with Aaron Wainwright and Tommy Reffell.
Tomos Williams is at scrum-half, with a centre pairing of Nick Tompkins and George North, and a back three that contains Liam Williams and wings Rio Dyer and Louis Rees-Zammit.
Wales need a point to seal top spot in the pool and set up a quarter-final that will likely be against either Argentina or Japan, who meet on Sunday in a winner-takes-all clash for second place in Pool D.
"We want to win the game, to carry on that momentum and re-establish the work we’ve done. I know one of their coaches well and they’ll be firing," King said.
Wales team:
15-Liam Williams, 14-Louis Rees Zammit, 13-George North, 12-Nick Tompkins, 11-Rio Dyer, 10-Gareth Anscombe, 9-Tomos Williams, 1-Gareth Thomas, 2-Dewi Lake (capt.), 3-Tomas Francis, 4-Will Rowlands, 5-Dafydd Jenkins, 6-Aaron Wainwright, 7-Tommy Reffell, 8-Taulupe Faletau
Replacements: 16-Elliot Dee, 17-Nicky Smith, 18-Henry Thomas, 19-Christ Tshiunza, 20-Taine Basham, 21-Gareth Davies, 22-Sam Costelow, 23-Mason Grady.
