Hartlett, 20, has been dogged by injury since being drafted by the Power with pick No.4 in the 2008 NAB AFL Draft.
The club's highest-ever draft pick overcame hamstring concerns to play 11 games in his debut season, but was restricted to just four appearances last year because of an ongoing quad complaint.
He was placed on a modified program this pre-season and had completed six months of solid training before breaking down on Monday morning.
This latest setback is expected to cost Hartlett up to three weeks on the sidelines, meaning he should be available for round three of the NAB Cup.
Injuries to Hartlett, Travis Boak (appendix), Jacob Surjan (knee), Jay Schulz (hamstring) and Jason Davenport (shoulder) will create opportunities for the club's younger players in the pre-season competition.
Forward Brett Ebert has described the Power's recent draft intake, which includes Sandringham Dragons defender Ben Jacobs, West Australian Ben Newton and Eastern Ranges duo Aaron Young and Cam O'Shea, as their best in four years.
Jacobs, 19, is considered a ready-made AFL player and football manager Peter Rohde said he expected at least one of the club's draftees to debut against the Crows and the Dees at AAMI Stadium on February 11.
"There will be opportunities for some [new players] but we also had a lot of young guys, who played when he had injuries late last year that will be pressing for selection," Rohde said.
"I'd expect one or two of the draftees to play in the NAB Cup, but not all of them."
