Saskatchewan rookie Craig Butler has been fined for an illegal hit during the Roughriders loss to Montreal last weekend.

The six-foot-two, 196-pound defensive back delivered a finishing hit on Alouettes receiver S.J. Green in the third quarter of Montreal's 39-25 win on Saturday.

The CFL deemed the hit to be illegal because Butler, while making a tackle, lowered his head and led with his helmet, which made primary contact with his opponent's helmet.

Green, who had four catches for 76 yards and a TD, was forced to leave the game and didn't return.

"These types of hits are illegal because they are dangerous and pose a serious risk of injury to players," said Kevin McDonald, the vice president of football operations for the CFL.

Butler, who was Saskatchewan's first pick (12th overall) in this year's CFL draft, was replacing injured starter James Patrick.

The amount of the fine was not disclosed by the CFL.