INJURY-PLAGUED Western Bulldogs midfielder Lin Jong has suffered a major hamstring blow after being forced from the field in the Dogs' match simulation this week.

Jong, 25, is set to miss up to 10 weeks after scans on Friday morning confirmed a high-grade hamstring tear.

The setback will rule Jong out of the Dogs' season opener against Sydney and place his first half of the season in doubt.

It comes after Jong played just 10 games last year on his return from a ruptured ACL before sustaining a broken collarbone in round 15.

Meanwhile, draftee Buku Khamis is also expected to be sidelined for up to two months after straining his PCL in Thursday's session.

The pair will join premiership ruckman Tom Boyd in the rehab group as he continues to overcome an ongoing back complaint.

Boyd remains on a modified program away from the main group and appears unlikely to line up in round one.

Speedster Jason Johannisen has been reduced to a moon boot, nursing an ankle syndesmosis injury sustained in training last week.

The Dogs are hoping to get a clearer understanding of a return timeframe by next week when he removes the boot, however Johannisen is in doubt for the start of the season.

Fellow premiership star Liam Picken is also yet to take part in contested drills, still suffering headaches from concussion symptoms that ruled him out for the entire 2018.