The club announced on Tuesday afternoon that Lobbe had ruptured his posterior cruciate ligament while playing for Port Adelaide's reserves side against Sturt in the SANFL.

He had been struggling to find form and had been dropped from the senior side.

Power's head of high performance, Darren Burgess, told the club's website Lobbe would not need surgery and would instead go straight into rehabilitation.

"It's a fairly standard rehab program that he'll do, he'll be in a knee brace for about six weeks, and will commence running in 6-7 weeks," he said.

His injury leaves Port short of options in the ruck as former Bomber Paddy Ryder is suspended for the season for his involvement in Essendon's 2012 doping program.

Youngster Dougal Howard, who rucked in the Power's win over Richmond over the weekend in just his second AFL match, is likely to see much more game time this season as a result.

One of three teams that is 3-3, Port Adelaide will play Brisbane at the Adelaide Oval on Sunday.