White to move and win

White to move and win.

White to move and draw

White to move and win.

White to move and draw.

FEN:8/5K2/7p/7k/p7/N7/8/8 w - - 0 1

White to move and draw.

How can White stop the e-pawn from Queening?
The interesting solution to this problem begins with 1.Bg4! If Black takes the Bishop than after 2.f3+ either 2...Kf4 or 2...Kh4 White is able to pick up the e-pawn and the game is then an easy draw.
But what happens if Black simply ignores the Bishop and Queens the e-pawn immediately?
1...e1=Q 2.h3!
The Black King is now imprisoned in a nice little tomb and there is nothing that he can do about it. Black's Queen by herself will be able to make no headway at all against White's King.
With care, White can simply shuffle his King back and forth on e1, e2, e3, and f3. If the White King could ever be stalemated in the corner, then White would be forced to move the Bishop and subsequently the Black King could escape. Black is unable to force this however, and so the result is a draw.
Source: Mate in 131

White to move and win