As an Emperor Lord, the Underworld Emperor's mental fortitude was beyond question. Ordinary people could not possibly compare to him; states such as wavering and confusion should have been almost impossible for him.
Yet Ye Xiwen's single thunderous shout had shaken his mind. That alone was already unbelievable.
It also proved that the Underworld Emperor was not as unconcerned as he appeared. Ye Xiwen's fierce pursuit had still dealt him a tremendous psychological blow.
Even if it was only a trace, it was enough.
More importantly, Ye Xiwen had broken through to the Second Stage in such a short time. To the Underworld Emperor, this was an immense deterrent. When he had broken through to the Second Stage, he had spent dozens of times longer than Ye Xiwen. Not to mention that, in the Second Stage, his strength had been far inferior to Ye Xiwen's.
For a powerhouse like him, this was an enormous shock as well.
After all, they were both Emperor Lord-level figures. Who would submit to another? Within the same realm, who was worse than whom? No one would readily admit it.
Although he had no way of returning to the Second Stage to contend with Ye Xiwen, he might deceive others, but he could not deceive himself.
That was the true reason his Dao heart had wavered. He was actually not the strongest—this was the problem.
An Emperor Lord meant the strongest. Within the same realm, no one would admit that they were inferior to another.
"A good opportunity—now!" Ye Xiwen seized the chance in an instant. This was precisely why he had said those words: to end the battle swiftly and kill him completely.
Otherwise, even if Ye Xiwen was confident of killing the Underworld Emperor, he did not dare claim that he could retreat