After Zhou Tian entered his personal world, the demigod, believing it impossible for Zhou Tian to defeat him in that world and confident he could prevail, saw no further reason to block Zhou Tian and instead thought about how he could kill him.
This change in thought directly altered the demigod's actions at that moment. Initially, the demigod's only thought was how to stop Zhou Tian. Thus, at the time, the demigod had no intention of engaging in a hard fight with Zhou Tian. Facing Zhou Tian, the demigod had no plans to confront him directly, fearing nothing more than blocking Zhou Tian's advance.
But now things were different, since he planned to deal with Zhou Tian, how could the demigod possibly avoid contact with him? With his mind set on trapping Zhou Tian in his personal world, the moment Zhou Tian entered, the demigod promptly launched an attack.