MIDFIELDER Christian Salem was best on ground until he was concussed at the 25-minute mark of the second quarter of Casey's 42-point preliminary final win.

The 21-year-old, who was precise by foot from the outset with his 15 disposals and six inside 50s, landed head first as he was brought to ground in a tackle.

It was a disappointing end to Salem's afternoon after he made a perfect start with his disposal efficiency and willingness to drift back to help his teammates in defence.

Salem was alert and talking to the medicos in the rooms.

On a better note, experienced defender Lynden Dunn starred with 25 possessions and 13 marks, and repeatedly repelled Williamstown's attacks inside 50.

The 29-year-old also drifted forward to kick a superb running goal from well outside 50m in the opening term.

Tough nut Clayton Oliver laid strong tackles and had 24 touches, ball-winner Alex Neal-Bullen was reliable as ever with a team-high 29 disposals, and big man Jake Spencer proved too strong in the ruck.

Out-of-contract midfielder Jack Grimes was a late withdrawal from the game due to illness.

Casey will take on Footscray in next Sunday's VFL Grand Final at Etihad Stadium.