However, physio Jon Fearn believes that the damage is not too serious, the striker may even be fit for Saturday's clash with SSV Reutlingen.
Bas spent the summer resting after straining his cruciate ligaments at the end of last season. After a long time out recuperating there were some worried faces in the Royals camp yesterday who thought Savage might have suffered a recurrance of his old injury.
Reading physio Jon Fearn told readingfc.co.uk: "When I went on I was quite concerned as he seemed to be in quite a lot of pain, but the early signs are good."
"It looks like he's hyper-extended his knee and jarred the joint - there's no cartilidge damage or cruciate damage taht I am concerened about. Everything seems stable but he might be stiff for a few days.
"At best he'll be out for maybe one or two days - at worst three of four."