MELBOURNE, AUSTRALIA - JULY 07: Jason Johannisen of the Bulldogs looks to pass the ball during the round 16 AFL match between the Western Bulldogs and the Hawthorn Hawks at Etihad Stadium on July 7, 2018 in Melbourne, Australia. (Photo by Quinn Rooney/Getty Images)

The Western Bulldogs will be without Jason Johannisen for this weekend's clash against Fremantle, with the premiership Dog sidelined with an ankle issue.

Laitham Vandermeer is set to replace Johannisen in the selected 22, lining up for his seventh game this season and his first since Round 8.

Johannisen has played seven games for the Dogs this season, the bulk of that coming in the latter half of the year after a calf injury left him sidelined prior to Round 14.

The Dogs haven't confirmed if the ankle injury will leave the 29-year-old sidelined for just the one match.

Johannisen's absence will add to several changes for the Bulldogs heading into Round 21, with Sam Darcy named as an inclusion for his debut match. Adam Treloar and Alex Keath have also been named as in's, with Buku Khamis, Mitch Hannan, Robbie McComb and Ryan Gardner making way.

The Bulldogs will host Fremantle at Marvel Stadium on Saturday afternoon, with the siren set to sound at 4:35pm (AEST).