Forced mate with 2 knights?!

I've purchased a couple of books recently, including "Chess Strategy for Club Players" by Herman Grooten. While I have yet to work my way into the book (let alone through it) I did discover an amusing story (which came via Time Krabbe) from the 1953 Candidates Tournament. In the diagrammed position Najdorf decided to end the game with 1. ... Rxf4+ 2.Kxf4 Rxg7 3.Nhxg7+. He apparently thought this was quite amusing, but for some reason Kotov, his opponent, played on. He asked Kotov why he was playing on in a theoretically drawn position. Kotov then informed him someone in Tbilisi had finally found a way to win this difficult position! It was only after the blood had drained from Najdorf's face did Kotov let him in on the joke by offering a draw.