The victim suffered serious injuries and eventually found aid by knocking on the door of a house.
Earlier in the week, police said they believed the victim had been blindfolded, with the offenders making demands for his money and phone.
The 87-year-old man told police he was threatened repeatedly and had his clothing ripped.
Det Insp Emma Hulston, from Greater Manchester Police, said: “While this is obviously a shocking incident for the local community, we do currently believe that this is an isolated incident with no wider threat to the public.”
She appealed for information and the force has opened a major incident portal, external into which details can be submitted.
