Winawer Variation, Fingerslip Variation, Kunin Double Gambit

In the Kunin Double Gambit Black leaves g7 hanging and wins a second pawn with 5...Qxd4. White is two pawns down but well ahead in development. The usual reply is 6. O-O-O, which puts the rook behind the d2-bishop so that a bishop move would uncover an attack on a queen short of safe squares. 6. Nf3 often leads to a queenless middlegame. The name comes from Kunin–Oschengoit, 1958, but the line had already appeared in Marshall–Chigorin, 1901, and Boleslavsky–Bronstein at the 1950 Candidates.