When does Rainsford feel fear for the first time?

In Part V, he encounter with Zaroff filled Rainsford with a terror that he had never known. It was this overpowering emotion that drove Rainsford into a heightened state of awareness. Finally realizing that the only way to beat Zaroff at his game was to be the smarter hunter, Rainsford changed his approach. Rainsford begins to hunt Zaroff with the same amount of passion as Zaroff is hunting him.