Scotch Variation, Belgrade Gambit

The Belgrade Gambit meets 4...exd4 not with a recapture but with 5. Nd5. The knight steps away from the d4 pawn's attack to a central post, while the e4 pawn loses its defender and Black keeps the extra pawn on d4. White trades material for piece activity and the chance to drag the opponent into unfamiliar complications. It is played far less often than 5. Nxd4, and with accurate play Black equalizes; engines rate the position roughly level. The first recorded game is Richter–Becker, Berlin 1938. The name comes from the 1945 Belgrade championship, where Mihailo Trajkovic used it against Miroslav Radojcic, who adopted it himself in that year's Yugoslav championship.

Online, the most frequent replies are 5...Nxe4 and 5...Nxd5, the latter heading for an early queen exchange, and White scores well against both. After 5...Nxe4 6. Qe2 the knight is pinned. In the Modern Defense, 6...f5 7. Ng5, the natural 7...Be7 runs into 8. Nxe4 fxe4 9. Qxe4 O-O 10. Bd3, with a strong initiative for White. The main line is the modest 5...Be7, which prepares castling and avoids complications. The reply 5...Nb4, threatening ...Nxd5, is considered the most testing.