The shortest decisive tournament game that was decided because of the position on the board (i.e. not because of a forfeit or protest) is Z. Đorđević–M. Kovačević, Bela Crkva 1984. It lasted only three moves (1.d4 Nf6 2.Bg5 c6 3.e3 Qa5+ winning the bishop), and White resigned. This was repeated in Vassallo–Gamundi, Salamanca 1998. (In a number of other games, White has played on after 3...Qa5+, occasionally drawing or even winning in this line.) The shortest game ever lost by a grandmaster because of the position on the board was by future world champion Viswanathan Anand, who resigned on move 6 against Alonso Zapata in 1988 (1.e4 e5 2.Nf3 Nf6 3.Nxe5 d6 4.Nf3 Nxe4 5.Nc3 Bf5?? 6.Qe2 winning a piece, since 6...Qe7 is answered by 7.Nd5 Qe6 8.Nxc7+).