No Living Man

[Lhunardawen]

In light of this discussion, I saw this in The Siege of Gondor:

The Nazgul screeched and swept away, for their Captain was not yet come to challenge the white fire of his foe.

In this situation, Gandalf did hinder WK, but there seems to be a rematch in sight because of the word yet. But they never meet again, as we see later on in the story. Can we then say that Gandalf has successfully hindered WK as opposed to WK's later claims as he conversed with Eowyn? After all, Gandalf here is not a man...or is he?