Billy Vuniopla could be ruled out of England's final pool stage match against France after he was seen wearing a moon boot.
The No. 8 injured his ankle in England's Pool C clash with Argentina on the weekend and was substituted at half time.
The 26-year-old was unable to train with the rest of the England squad on Tuesday and underwent a scan on his ankle.
But when scrum coach Neal Hatley was asked by the media if Vunipola was injured, he said: "No. He is just walking around fine."
A photo by an England fan circulating on social media showed Vunipola wearing a protective moon boot on his left leg while talking to England medic Rob Young at the team's hotel.
Speaking on Tuesday, England's assistant coach Scott Wisemantel said Vunipola completed a "recovery and rehab" session but he didn't give any details about his scan.
Wisemantel added: "At this stage all 31 players are available and we will make a call late Wednesday early Thursday, but if there is any doubt we will rest him."
The reason given for the protective boot was "as a precaution" and there was no suggestion that Vunipola would not be fit for England's quarter final on October 19/20.
"We are being overly cautious, and if there is any risk that Billy is not going to be 100 per cent we will rest him,” Wisemantel said.
England face France on Saturday to decide who the winners of Pool C will be.
A first place finish for England would likely see them face Australia in the quarter-finals, with reigning champions New Zealand in the semi-finals.
But if they finish second in the group, they could face Wales in the quarter-finals and Ireland, hosts Japan or South Africa in semi-finals.
A piece of statistical analysis has shown that England are more likely to make the final if they finish second in the pool.
