Ah-hah, he's found a weak spot indeed. This close, Aslan's headbutt doesn't have enough momentum to do much more than knock Thor's breath from his lungs, though the meaty strikes of the Lion's paws are not as restricted, battering at Thor's sides powerfully enough that it might leave bruises, if he lets the assault continue.

No matter. Thor has a new cunning plan.

He abruptly jolts a knee up toward Aslan's chin, simultaneously using his hold on his opponent's ears to try forcing the Lion's entire head to the side enough that he might be able to wriggle out of Aslan's hold, if he's fast enough.