The Celestial Sect of Wonders' exploits were beyond expectations even for Yan Nanlai.
Although he was heading speedily for the distant horizon, Yan Nanlai's Awareness was paying attention to the battlefield behind him as well. He has a rough estimate of the strength of the Hades masters who pursued him from Mount Baiyun as well.
Especially Zhanming, who was of Cardinal Tribulations Beginning Stage. He previously participated in the Battle of Mount Baiyun as well; thus, Yan Nanlai was fully aware that the demonic powers of this Hades was so strong that he could more or less match up against the White Tiger Grand Sage. The gap, if it existed, was microscopic; he has the ability to go up against the White Tiger Grand Sage, and as for the actual result, it could only be determined by an actual duel.
The events of the battle thereafter proved Yan Nanlai's hypothesis as well.