[Gusty]

With the following blow, both Swiftfang and Burrpaw had collided together; both toms had been jumping straight at each other and were both slammed with sudden force. Burrpaw was most likely knocked by Swift's large weight and structure, while Swift was thrown off by Burrpaw's full-of-power move.
As a result, the warrior was thrown backwards a few feet and landed on his back. While he was indeed safe and unharmed, it did leave his belly exposed.