[Kronos]

Lets take a look at this quote that he gives;

Of the others only Gandalf might be expected to master him – being an emissary of the Powers and a creature of the same order, an immortal spirit taking a visible physical form.

Now even at face value this is not proof that Gandalf would defeat Sauron one on one. Firstly the quote says might, which implies a degree of doubt.

However when you examine the context of the quote it just gets more and more doubtful.

Firstly the quote is comparing Gandalf's chance of beating Sauron to the other non-mortals (i.e. Elves and Istari). Of course his chance is going to be higher. Of course of all of them only Gandalf might be able to do it. We already know that Gandalf the White is now the greatest of his order and so that makes him most likely amongst the Istari and of the Elves only Galadriel even comes close.
So saying that of these Gandalf was the only one who might be expected to master Sauron. Hardly a great leap.

But it gets better yet. The quote is actually also referring to these peoples chances if they had the One Ring to use against Sauron. Thereby tipping the balance considerably.

So in summation the quote indicates that with the One Ring Gandalf might be expected to master Sauron in comparison to the other immortals of Middle Earth.

And this Legolas turns into

Tolkien said Gandalf could beat Sauron

Tolkien *did* say Gandalf could beat Sauron. It could go the other way too, but the fact remains, Gandalf could beat Sauron. He had the ability to. He could have. Tolkien said so; Tolkien created this world and decides such things. How is this disputed?