SimonWebbsTiger: the Chameleon Trap
Here there is the move 6...N-QR4, which I took the risk of trying out against Korchnoi; it was very little known in theory at that time and completely untested in practice....
But I practically had no choice: Korchnoi, previous to our game, had crushed one opponent after another with the standard 6...P-KR3 7. BxN QxB 8. N-Q5 etc.
Not so long ago, when Korchnoi had already become a serious contender for the world chess crown, I happened to ask him: 'Why don't you play the Two Knights' anymore these days?' The grandmaster looked at me in amazement and muttered: 'Because of 6...N-QR4, of course. You mean to say you didn't know that yourself?...'
[An extract of one of the many amusing game introductions from "200 Open Games" by Bronstein (Batsford 1974).]