Portuguese Gambit, Classical Variation

The Classical Variation meets the Portuguese Gambit's 3...Bg4 by interposing the king's knight. Unlike 4. f3, which hits the bishop but takes f3 away from the knight, 4. Nf3 develops a piece and leaves the kingside pawns intact. It accepts a pin that White intends to break with Be2 before castling. The price is the d5 pawn: White makes no attempt to support it with c4, so Black can simply recapture and the gambit character largely disappears. Engines rate the position as slightly better for White, while results in online games are almost evenly split.

Black's usual choice is 4...Qxd5, centralizing the queen and eyeing d4 while the bishop keeps the knight pinned. Recapturing with the knight, 4...Nxd5, transposes to the Gipslis Variation of the Modern Scandinavian and scores somewhat better for White. A third option clarifies matters at once: 4...Bxf3 5. Qxf3 Qxd5 6. Qxd5 Nxd5 gives up the bishop pair to reach an early queenless position in which Black's development is comfortable.