The Western Bulldogs have been dealt a big blow amid their five-game winning streak after a serious injury.
Johannisen has returned to his rebounding best this season after being moved back to defence by coach Luke Beveridge.
He was subbed off midway through the third quarter of Saturday’s win over Adelaide in Ballarat after feeling at his hamstring and Beveridge’s worst fears were realised on Monday.
The scans showed “extensive damage” requiring a lengthy stint on the sidelines.
“Unfortunately, our great win against the Crows was soured by a hamstring injury to JJ in the third quarter,” Bulldogs’ Head of Sports Medicine, Chris Bell, said.
“Being an over-stretching injury whilst at speed, our clinical suspicions of a high-grade injury were confirmed with the MRI that showed extensive damage.
“JJ is the ultimate professional and will get to work with our rehab team to get back playing this home and away season, but we anticipate that he will miss 8-10 games.”
Other then Johannisen, the Bulldogs emerged from the clash in Ballarat without any other serious injury concerns after captain Marcus Bontempelli was cleared of an ankle injury.
The Bulldogs have scorched in to sixth place on the AFL ladder on the back of five-straight wins.