Vienna Defense

Instead of accepting the second pawn with 4...exf3, Black develops the light-squared bishop to f5. From there it supports the pawn on e4, so that 5. fxe4 can be met by a recapture. Matthias Wahls recommended the line in Modernes Skandinavisch and regarded it as a refutation of the gambit. Engines give Black a slight edge, though online results are close to level. The position also arises from the Zeller Defense via 3...Bf5 4. f3 Nf6.

The most common reply is 5. fxe4 Nxe4 6. Qf3, a pure gambit treatment. After either 6...Nxc3 or 6...Nd6 the play becomes complicated, and Black often gives back the b7-pawn to catch up in development. The main line, 6...Nd6 7. Bf4 e6 8. O-O-O c6 9. g4 Bg6 10. Qe3 Be7, leaves Black solid but White with enough compensation. The alternative 5. g4 Bg6 usually aims to win the pawn back. One example is 6. g5 Nd5 7. Nxe4, where Black obtains the initiative and the better structure in return. White can also keep the pawn sacrificed with 5. g4 Bg6 6. h4, which leads to sharp play with roughly equal chances. Of the other moves, 5. Bg5 is frequent, and 5. Bc4 leads to the Soller Attack of the Zeller Defense.