From what we have been told, the Balrogs were Maiar, like Sauron, and were also corrupted by Morgoth.
It's possible the Balrog in question might have had a chance against Sauron. While I don't have his
Letters to hand, I recall Tolkien saying that the only being who had a chance to defeat Sauron in personal combat while using the One Ring was a Maia, Gandalf. Might that Balrog, also a former Maia, have a similar chance?
