Vikings defensive end Jared Allen insisted Sunday evening he meant no harm with his blindside block of Bears guard Lance Louis. But plenty of harm was done, with Louis tearing the anterior cruciate ligament in his left knee and being put on injured reserve Monday.

It's a huge blow to the 8-3 Bears, whose offensive line was already in disarray due to injury and poor play. Louis had become the unit's most dependable player.

But his season ended on an Antoine Winfield interception with 12:57 to play in the third quarter Sunday. During Winfield's 31-yard return, Allen left his feet and used his right forearm to deliver a crushing shot on Louis.

A day later, Chicago coach Lovie Smith questioned Allen's approach, his discontent even more apparent given the end result for Louis.

"Jared Allen plays the game a certain way. He's a good player in our league," Smith told reporters in Chicago. "But I think there's some plays when you look at them again, you say, 'Hey, we could have done without [that]. I think our game can do without that play."'

The NFL will review the play and Allen could face a steep fine for delivering an illegal hit on a defenseless opponent.

The league's 2012 playing rules have plenty of provisions to protect defenseless players, a designation Louis fit as "a player who receives a blindside block when the blocker is moving toward or parallel to his own end line and approaches the opponent from behind or from the side."

NFL rules also identify it as "an illegal launch if a player leaves both feet prior to contact to spring forward and upward into his opponent." Allen did so with the shot on Louis, though he didn't draw a penalty on the play.

Bears defensive lineman Israel Idonije also questioned Allen's methods. As Idonije told the Chicago Sun-Times: "Lance is quick. He's fast. But it's not a situation where he was just blazing and [Allen] had to lay him out to make a saving play. He hit him that way because he chose to hit him that way."