Walsh,who has been managing his back this season following surgery,clutched at his hamstring before half-time against West Coast.
Silvagni was subbed out early with what the club initially hoped was a jarred knee,but there remained uncertainty on Sunday as to the seriousness of the injury,with a club source saying they were still waiting on results.
Small forward Motlop also hurt his calf and was taken from the game as a precautionary measure as the Blues thrashed West Coast.
It is bad luck for the Blues,who expect to have their skipper Patrick Cripps back after he was sidelined against the Eagles. Likely best and fairest winner Adam Cerra is also in line to return,while Jack Martin is expected to be fit after failing a fitness test ahead of Saturday’s game.
Ruckman Marc Pittonet also played in the VFL as he returns from a knee injury.
Meanwhile,Brisbane young gun Will Ashcroft has ruptured his ACL,with scans confirming the bad news for the 19-year-old.
Ashcroft injured his right knee midway through the fourth quarter in Saturday’s win over Geelong at the Gabba when he charged in to contest a ground ball in the centre of the ground.