Mike Tindall admits the race to prove his fitness for England's World Cup defence will go down to the wire.
Gloucester centre Tindall broke his leg in April but was recently included in Brian Ashton's preliminary 47-man party for the tournament in France.
England play three warm-up Tests in August but only two - against Wales on August 4 and France a week later - fall before the August 14 deadline when the final 30-strong squad must be named.
Facing Les Bleus at Twickenham on August 11 looks Tindall's most likely comeback date but there is little margin for error with Ashton forced to whittle down his options just three days later.
'It's going to be close,' Tindall, a World Cup winner in 2003, told BBC Radio Gloucester.
'I'm hoping to start running in a month or so and I'm hoping to get in one of the warm-up games.
'We'll know in six weeks whether I'm going to make it. Fingers crossed.'
England's final World Cup tune-up is a second Test against France, in Marseille on August 18.
The squad depart for an eight-day training camp in Portugal on Friday but Tindall will remain at home to continue his rehabilitation.