Pan Gu hid away.
Actually, he was still in Pan Gu's secret realm. However, wanting to keep his whereabouts unknown, he hid away to prevent Ye Fan from finding him, allowing him to proceed with his own plans covertly.
"Ye Fan is becoming increasingly irrational; this kid clearly wants to usurp my position of dominion. By withdrawing now, I'm merely giving him the chance to resolve the celestial trial!"
Pan Gu seemed to be comforting himself; he did not need to justify himself to anyone. His cultivation was already powerful enough to destroy the mortal world. However, he was also aware that after the celestial trial, his own life would come to an end.
While Pan Gu was hiding, Ye Fan was still searching for him using his Spiritual Sense.
Pan Gu did not escape Fu Xi's tracking. Despite his wish for Fu Xi not to find him, Fu Xi appeared before Pan Gu.
