England centre Mike Tindall hopes to play in one of England's August warm-up Tests to prove his fitness for the World Cup, which starts on 7 September.
Tindall was still on crutches in May
"It's going to be close," Tindall, who is fighting his way back to fitness after breaking his leg in April, 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."
Tindall, who was injured in a Premiership game against Newcastle, is unlikely to be available for England's first warm-up Test against Wales on 4 August.
There is only one more Test - against France at Twickenham on 11 August - before head coach Brian Ashton has to name his final 30-man squad on 14 August, with England's final Test before the World Cup in Marseille on 18 August.
Tindall was named in Ashton's initial 47-man World Cup training squad, but has remained at home to continue his rehabilitation in the gym.
The rest of the players are currently working with the Royal Marines before flying out to Portugal on Thursday for an eight-day training camp.
The 6ft 2in, 16 stone Gloucester centre was part of England's World Cup-winning team in 2003 and has won 53 caps.