At the same time he struck a terrific cutting stroke with his left paw.
Thor was a digger, and his claws were dulled; the black was not a digger, but a tree-climber, and his claws were like knives.

And like knives they buried themselves in Thor's wounded shoulder, and the blood spurted forth afresh.
With a roar that seemed to set the earth trembling, the huge grizzly lunged backward and reared himself to his full nine feet.

He had given the black warning.

Even after their first tussle his enemy might have retreated and he would not have pursued.

Now it was a fight to the death! The black had done more than ravage his cache.