Pook's involvement in Saturday's 1-1 draw at local rivals Hereford ended after just 11 minutes after he suffered medial knee ligament damage and fortunately not cruciate damage.
The summer signing will now be out for a month as Martin Allen's side look to extend their unbeaten start to the season in League Two. David Bird becomes the likely candidate to replace him.
Striker Elvis Hammond recovered sufficiently from his clash with an advertising board to start at Edgar Street, while Oliver Bozanic returned to the Robins XI after his international exploits for Australia. Both are expected to continue this time around.
Winger David Hutton will be pressing for involvement after starting from the bench against the Bulls, while Marley Watkins will be hoping to reclaim his place in Allen's matchday 18.