4.d5 Ne7. Now the game may continue in "Tango" fashion, for example with 5.Nf3 Ng6, or transpose to the King's Indian Defense with, for example, 5.Nf3 d6 6.e4 (6.Bg5!?) g6 7.Be2 Bg7 8.0-0 0-0, reaching the main line of the King's Indian by transposition. Another interesting but relatively unexplored idea is 3...e6, allowing White to play 4.e4 (other moves such as 4.d5, 4.Bg5, 4.a3, 4.f3, and 4.Nf3 are also possible), whereupon Black follows up with 4...d5. From that position, the main possibilities are 5.e5 (the main line), 5.exd5, 5.cxd5, and 5.Bg5. These possibilities can also be reached via transposition from the Mikenas–Carls Variation of the English Opening (1.c4 Nf6 2.Nc3 e6 3.e4), although if Black wishes to play this way, the optimal move order is 1.d4 Nf6 2.c4 e6 3.Nc3 Nc6. 3.d5 This ambitious move is but rarely seen. Black normally responds with 3...Ne5. Then after 4.e4 (inviting 4...Nxe4 5.Qd4 winning a knight), Black struck back in the center with 4...Ng6 5.f4 e5 in the seminal game Sämisch–Torre, Moscow 1925. Orlov considers both Torre's fourth and fifth moves inferior, however. He and Palliser both recommend 4...e6 instead, after which play can become extremely . For example, Elburg–Simmelink, correspondence 1999 continued 5.f4 Ng6 6.Bd3 exd5 7.e5 Ne4 8.cxd5 Qh4+ 9.g3 Bb4+! 10.Bd2 (Better is 10.Nc3 Nxc3! 11.bxc3 Bxc3+ 12.Bd2 Bxd2+ 13.Qxd2 Qe7 14.Nf3 d6 15.Bb5+! Kf8 16.Qc3 with some practical chances for the sacrificed pawn.) 10...Nxg3 11.Nf3 (first diagram) Nxf4! 12.Bf1! (12.Nxh4?? Nxd3!; 12.Bxb4? Nxd3+ 13.Qxd3 Qxb4+ is hopeless for White.) 12...Bxd2+ 13.Nbxd2 (second diagram; 13.Qxd2? Nxf1+ 14.Nxh4 Nxd2 is winning for Black.) Qh3! 14.Rg1 (White cannot take either of Black's two hanging pieces: 14.Bxh3 Nd3#; 14.hxg3 Qxg3#. Nor is 14.Ng5 Qg2! any better.) 14...Nxf1 left Black with two extra pawns. References Bibliography Georgi Orlov, Black Knights' Tango, International Chess Enterprises, 1992. . Georgi Orlov, The Black Knights' Tango: Outwit Your Opponents from Move 2!, Batsford, 1998. . Richard Palliser, Tango! A Dynamic Answer to 1 d4, Everyman Chess, 2005. . External links Betwixt the Tango and the Budapest (arguing that 3. Nf3 does not prevent 3 ..e5) Chess openings 1925 in chess