Deledio strained his calf in round one against Carlton and has missed the past two weeks with the injury.
He was originally expected to only miss one to two weeks, but coach Damien Hardwick said the injury has not recovered as quickly as first thought.
“He’s probably unlikely next week also … it’s been a bit of a painful process for us.
“The good thing about Brett is he’s probably flat on the inside [but] you wouldn’t know on the outside,” Hardwick said.
It will only be the seventh match Deledio has missed at Richmond since 2007.