England centre Jonathan Joseph could yet play in Saturday's crunch World Cup clash with Australia at Twickenham.
The Bath back was given a gentle reintroduction to the group on Tuesday morning, offering England hope he may be fit to return for the Pool A match which the hosts realistically must win to have any chance of progressing to the last eight.
He missed the 28-25 defeat by Wales because of a pectoral muscle injury and was replaced by Rugby League convert Sam Burgess.
Joseph did not join the squad for the afternoon session but if fit is an automatic selection at outside centre and the make-up of England's midfield hinges on his availability.
Number eight Ben Morgan has recovered from his knee problem and is available to play, which is welcome news after Billy Vunipola was ruled out of the remainder of the tournament with a knee injury.
But lock Courtney Lawes and scrum-half Ben Youngs are unlikely to recover in time from their respective knee and ankle issues.
England name their team on Thursday morning and Catt added: "We'll see who is fit and healthy and make a final decision.
"Whoever we decide to select or whoever is fit, we have total belief we can go and score tries against teams.
"Australia love an open game, but we are also capable of scoring tries."