One of the most bizarre endings ever to a Candidates Match (with the possible exception of Smyslov's roulette wheel in 1983).
In a 12 game Quarter-Final match in Reykjavik (a place where Spassky already had some unpleasant memories, Hort succeeded in equalizing the scores just before the end. Match rules then called for a series of 2-game mini-matches to be played until somebody won. The first one, in Games 13 and 14, produced two draws.
In the second tie-breaker match, with one minute left to make 5 moves in Game 15, Hort achieved a totally winning position... but didn't move! Spassky, who mistakenly believed he was winning, thought Hort was psyching himself up for defeat. No, Hort saw the win, but became so excited at the sudden turn of events, that he forgot to move, and forfeited in a winning position!!
Hort still could have equalized again with a win in Game 16, but after a reverse like this, I don't think I have to tell you that that didn't happen.