He hasn't lost yet, he can still continue.
The rock ceiling above finally couldn't bear the weight and began to collapse, countless fragments crashing down, completely destroying the underground river. Their struggle was interrupted by this sudden change, as the river water surged and crashed them against the protruding rocks at the riverbed, finally sinking below.
In the dark depths, the blazing fire continued to burn. Like the madness of drowning ones before death, their figures twisted together. After a brief pause, they fought each other in the turbulent water, this was no longer a battle between humans, it was more like a beastly fight.
Heavy rubble pressed upon them, dark red blood flowed out from the gaps in their armor and flesh, drifting with the waves, crashing against the rock walls with a huge impact difference.