Budapest Gambit - Rubinstein Variation 3...Ng4 4.Bf4

Rubinstein Variation 3...Ng4 4.Bf4

1.d4 Nf6 2.c4 e5 3.dxe5 Ng4 4.Bf4

This move sequence is called the "Rubinstein variation" in reference to the famous game Rubinstein–Vidmar (Berlin 1918) when 4.Bf4 was first employed. Various authors consider this move to be the most dangerous for Black. It aims to answer 4...Bc5 with 5.e3 without blocking the Bc1, contrary to what happens in the Adler variation 4.Nf3. Another point is that in the Adler variation White faces the risk of a strong attack against his kingside (see section "Budapest rook"), while in the 4.Bf4 variation this is seldom the case because the Bf4 is well-placed to protect White's kingside. On the other hand, the early development of the bishop means that White is more vulnerable to the check Bf8–b4+, the b2-pawn is not defended, and in some rare cases the Bf4 can become subject to attack.

Apart from the sideline 4...g5, the main line continues with both players developing their pieces around the e5-pawn with 4...Nc6 5.Nf3 Bb4+ when White has an important choice between the moves 6.Nc3 and 6.Nbd2, each leading to extremely different play. With 6.Nc3 White acquiesces to the breakup of his queenside pawns in return for a material advantage of one pawn, the bishop pair and active play in the centre. With 6.Nbd2 White gives back the gambited pawn to keep a healthy pawn structure and acquire the bishop pair. After 6.Nbd2 Qe7 White generally plays 7.a3 to force the immediate exchange of bishop for knight, gaining the bishop pair, a spatial advantage and chances for a minority attack on the queenside. White can also try 6.Nbd2 Qe7 7.e3 to win a tempo over the 7.a3 variation, though he may end up with the exchange at d2 made in less favourable circumstances, or not at all. The maverick gambit 6...f6 also exists.