PORT Adelaide defender Jasper Pittard will have a delayed start to the season, with his latest hamstring injury set to keep him sidelined for up to five weeks.

The Power provided an update on Pittard's injury on Monday night, stating he was expected to miss between four and five weeks.

The 26-year-old injured his hamstring during the third quarter of the Power's win against Adelaide in their JLT Community Series game at Alberton Oval on March 10.

It's the second year in a row that Pittard has picked up a hamstring injury during a pre-season game.

Last year, he injured his hamstring in the second quarter of his side's JLT Community Series match against Richmond in Mount Gambier.

Pittard made the 40-man All Australian squad in 2016, but struggled to recapture that form last year, when he was dropped from the team several times.

His absence opens the door for impressive youngster Riley Bonner to cement a spot in the Power's youthful backline.

The Power confirmed that skipper Travis Boak (hamstring) and midfield bull Sam Powell-Pepper (shoulder) would be assessed this week ahead of Saturday's round one clash with Fremantle at Adelaide Oval.

Second-year midfielder Willem Drew – the 33rd overall pick in the 2016 NAB AFL Draft – is sidelined with a foot injury, while rookie-listed midfielder Cameron Hewett is out with a shin complaint.

The Power still don't have a timeline for the return of experienced defender Matthew Broadbent, who required a second bout of surgery on his troublesome ankle.