PORT Adelaide midfielder Karl Amon will be sidelined for up to a month with a fractured patella.

Amon copped a knock to his knee in the Power's two-point loss to Geelong, and was a late scratching from last Thursday night's win over Hawthorn.

The Power's head of high performance Darren Burgess said it wasn’t thought the injury was as bad as scans have subsequently revealed.

"We felt it was a minor knock originally, but when he couldn’t come up for the match against Hawthorn we decided to get it scanned," Burgess said.

"The scans showed a fracture there, unfortunately it looks like a 3-4 weeker for him."

In better news, star midfielder/forward Chad Wingard is likely to return from a calf injury for Saturday night's game against Essendon at Etihad Stadium.

Wingard trained with the main group on Tuesday and will be assessed during the week.

"He got through training, trained really well and we're looking forward to hopefully selecting him if he pulls up well tomorrow," Power assistant coach Brendon Lade said.

"I'd say at this stage it would be (likely).

"He was probably the best on track today, the freshest of everyone out there and looked really good.

"Barring pulling up sore, he'll play."

Wingard's return could force Jimmy Toumpas out of the side.

Former Demon Toumpas, the No.4 overall pick in the 2012 NAB AFL Draft, picked up 26 possessions against the Hawks after getting called in as a late replacement for Amon.

"He came in and played the role for us," Lade said of Toumpas.

"He knows the wing role really well, he's been playing half-back for the Magpies (Port Adelaide's SANFL team), so for him to come in and do what he did was great for Jimmy and shows he can play a role in our team.

"It was more like for like.

"(Joe) Atley has been playing well, but he's more of an inside midfielder, so is (Jesse) Palmer. Jimmy's been playing on the outside as a wingman, half-back, so it was an easy choice."