Ba Song believed that Xiang Yu was the type of person who would rather lose his life than lose face, but obviously, he didn't understand Xiang Yu at all. In front of this bunch of bastards, Xiang Yu didn't need to save face, because he simply didn't care.
The kick just now had indeed startled Xiang Yu. If Ba Song had landed a solid kick, he might have lost his ability to fight. Therefore, he chose to retreat, using the backward motion to cushion the force.
Then, he would pretend to have lost his fighting capability and wait for Ba Song to lower his guard before delivering a fatal blow.
This battle plan flashed through Xiang Yu's mind, but when Ba Song's kick actually hit Xiang Yu's chest, he felt the force wasn't as great as he had imagined. Although Ba Song had kicked him away, Xiang Yu wasn't affected at all.
Given that, there was no need for him to pretend to have lost his fighting capability. He could just continue the fight on the ring.