PORT Adelaide defender Hamish Hartlett is set to miss the rest of the season with a suspected torn ACL in his right knee.

Hartlett injured his knee at training in a routine drill at Alberton Oval on Thursday morning.

It's a devastating blow for the 27-year-old, who courageously returned to the field after a massive head clash with Geelong superstar Patrick Dangerfield in last Saturday night's loss to Geelong.

"This is obviously a terrible blow for Hamish and the football club," the Power's general manager of football, Chris Davies said.

"It was an innocuous incident that caused the injury. He went to change direction and his leg gave way beneath him.

"We fear Hamish won't be back on the field for some time, but no doubt he'll continue to contribute as a leader of our football club."

Hartlett, who has played 153 games and is in the leadership group, will have scans to confirm the extent of the injury.

Who replaces Hartlett across half-back for Saturday's clash with North Melbourne at Etihad Stadium isn't a straight-forward decision.

Jasper Pittard would be the logical choice, but he played for Port Adelaide in its SANFL game against Sturt on Anzac Day.

It would mean Pittard would be coming off a three-day break, which would be unlikely given he has played two games since tearing his hamstring against Adelaide in the JLT Community Series.

Pittard also has a history of soft tissue injuries, so playing on the hard surface at Etihad Stadium would be a factor.

Former Gold Coast superboot Trent McKenzie would be another option, but like Pittard, he also played in the SANFL game on Wednesday.

Jimmy Toumpas was a late scratching from the SANFL game because of illness, but the former No.4 overall draft pick is expected to be available for selection.

A left-field choice could be Ugandan-born Category B rookie Emmanuel Irra, who caught the eye with several pieces of enterprising play against the Double Blues.

The Power held back winger Dom Barry and pacy forward Aidyn Johnson from the SANFL game.

One of those would come into the side for suspended forward Lindsay Thomas.