Rosentreter Gambit

The Rosentreter Gambit arises when White meets the Classical Variation's 3...g5 with 4. d4 rather than the more common 4. h4 or 4. Bc4. The central advance opens the c1-bishop's diagonal toward f4, so the gambit pawn can be targeted, and it also prepares a reply to the natural 4...g4, which is by far Black's most frequent choice. The resulting positions often resemble the Quaade Gambit.

After 4...g4 White has three main tries. The most popular is 5. Ne5, the Bird Gambit. After 5...Qh4+ 6. g3 fxg3 7. Qxg4, Black can trade queens with 7...Qxg4. The greedier 7...g2+ 8. Qxh4 gxh1=Q wins a rook, but after 9. Nc3 the position is complicated and Black must defend with great care. The Testa Variation, 5. Bxf4, and the Sörensen Gambit, 5. Nc3, both abandon the f3-knight in the manner of the Muzio Gambit. They seek an attack with the dark-squared bishop or the queen's knight respectively. Black's other replies to 4. d4 include 4...d6 and 4...Bg7. Engines give Black a slight edge, while online results are close to even.