He did not check himself, but drove in upon Spitz, shoulder to shoulder, so hard that he missed the throat.

They rolled over and over in the powdery snow.

Spitz gained his feet almost as though he had not been overthrown, slashing Buck down the shoulder and leaping clear.

Twice his teeth clipped together, like the steel jaws of a trap, as he backed away for better footing, with lean and lifting lips that writhed and snarled.
In a flash Buck knew it.

The time had come.