Anscombe suffered a groin injury while kicking in the warm-up ahead of Saturday’s 43-19 win over Georgia in Nantes, which elevated Biggar onto the bench even though he had been left out of the original matchday squad after suffering a pectoral injury when Wales thrashed Australia 40-6 in Lyon a fortnight earlier.
Wales, however opted not to bring him off the bench as Biggar had only returned to training last week, with third choice fly half Sam Costelow (22) playing the entire match instead.
Williams suffered a knee injury against Georgia, where unbeaten Wales made sure of top place in Pool C, but contact area coach and former international Jonathan Thomas told reporters on Tuesday all three could play in the first of the quarter-finals at Marseille’s Stade Velodrome.
"All those players at this stage are looking positive. It’s probably not as bad as first feared," Thomas said.
Williams had been on crutches after Saturday’s game but Thomas added: "The crutches makes it look worse. It’s just trying to offload pressure. He was jogging about with the medics."
Wales have also added called up Scarlets scrum half Kieran Hardy (27) after losing Taulupe Faletau (32) to a broken arm.
"It was a bit of a weird one, winning and topping the group but it was a sad feeling for losing Toby. He’s a big part of our squad. Everyone is gutted," said prop Gareth Thomas.
"Nothing changes for us. We haven’t really thought we’re underdogs or vice versa. We’re taking every game as it comes," he added.
