Gehrig was this week placed on the long-term injury list after battling arthritis in the hands, as well as groin problems for the early part of the season.
Much speculation has been made about Gehrig’s future with the Saints but Lyon would not say if he would return.
“He’ll be on the long-term injury list for eight weeks and we’ll assess it from there,” Lyon said.
“We had some really good discussions and there was the opportunity to rehabilitate his body and then take it from there.
“That is fundamentally the decision we’ve made and that is in the best interests of both parties.”
Lyon met with Gehrig on Monday and said he did not have to talk his full forward out of retirement.
Gehrig will join the rehabilitation program and work with the club’s younger players while he sits on the sidelines.
“We’re really pleased, it gives Fraser the opportunity to heal his body and continue to work with our young forwards. He’s got a lot of knowledge and he’ll be able to help in that aspect over the next eight weeks,” Lyon said.
In better news for St Kilda, captain Nick Riewoldt and defender Steven Baker are chances to return from knee injuries.
“[Riewoldt] is a really good opportunity to play. We’re really optimistic he’ll play but he’s got two more sessions to get through," Lyon said.
"Baker’s in exactly the same category.”
Midfielder Luke Ball will also play against the Brisbane Lions this week despite being seen wearing a moon boot at Monday’s training session.
The coach admitted an initial shock when first seeing Ball.
“I saw that I almost fell over,” Lyon said.
“He’s fine. If we had anything to hide and he was in any risk, he wouldn’t be out there at an open session with the moon boot.
“I think it highlights where AFL medical teams have gone ... any slight knock and they want to immobilise them. He had a knock on his ankle but it wasn’t dramatic. We wouldn’t expose it if it was dramatic.”
