The 31-year-old was supposed to play his first game since round four in Geelong's VFL team against Collingwood.
However he pulled up sore at training on Wednesday, casting doubt over when he'll return to the field.
Leading sports medico Dr Peter Larkins said while he hoped the latest setback was minor, it put Chapman back in the 'indefinite' category.
"Geelong won't want to rush him back until they think he can get through a match, and hopefully this is only a short-term setback," Larkins told AFL.com.au.
"This is a real surprise he didn't get through training and it's a real psychological setback for any player that thinks they've done everything right with an injury like this when they can't get up to the full capacity to train.
"It becomes an unknown. He's a week-to-week proposition. We don't know now."
Click here for Dr Peter Larkins' injury report
The Cats said on Thursday they would continue to take a conservative approach with the three-time premiership player.
"Whilst it is obviously disappointing for the club and Paul, we have said all along we would be ultra conservative with Paul," general manager of football Neil Balme told the club's website.
"Paul's approach to his rehabilitation has been second to none and we look forward to his return to competitive football."
Larkins said time was running out for Chapman.
"The fact is we're in round 17, which is making it much harder for him to get any reasonable match conditioning because you wouldn't expect he's going to play senior football in the next month even if he does get back to the VFL," he said.
"It's really disappointing because he's done everything so well and it's a real psychological hurdle now because the club really hasn't left anything untried for him."
Jennifer Phelan is a reporter for AFL Media. Follow her on Twitter @AFL_JenPhelan.
