Budapest Gambit - Adler Variation 3...Ng4 4.Nf3

Adler Variation 3...Ng4 4.Nf3

	a	b	c	d	e	f	g	h
8									8
7									7
6									6
5									5
4									4
3									3
2									2
1									1
	a	b	c	d	e	f	g	h

The Adler variation 4.Nf3

1.d4 Nf6 2.c4 e5 3.dxe5 Ng4 4.Nf3

The Adler variation is named after the game Adler–Maróczy, played at the 1896 Budapest tournament. White is ready to return the e5-pawn in order to develop his pieces on their best squares, i.e. the d5-square for the Nb1, the f3-square for the Ng1 and the a1–h8 diagonal for the Bc1.

Black can try the minor line 4...Nc6 that delays the development of its dark-square bishop, to develop it along the a1–h8 diagonal instead of the a3–f8 diagonal, depending on the circumstances. But the main line is 4...Bc5 to attack the f2-pawn, forcing 5.e3, blocking in White's bishop on c1, so that after 5...Nc6 White will not have enough pieces to protect his e5-pawn in the long run. Placing the bishop on the c5-square also has subtler points, as Tseitlin explains:

At first sight the bishop on c5 lacks prospects, being held at bay by the pawn on e3, and is insecure in view of the threat to exchange it by Nc3–a4/e4. In reality, posting the bishop here has a deep strategic significance. It holds up the advance of the e- and the f-pawns (assuming the white bishop will go to b2), and thereby secures e5 as a future knight outpost, which in turn restricts the activity of both White's bishops. As to the exchanging threat, the bishop may conveniently retreat on a7 or f8, or even in some cases remain on c5 with support from a pawn on b6.

	a	b	c	d	e	f	g	h
8									8
7									7
6									6
5									5
4									4
3									3
2									2
1									1
	a	b	c	d	e	f	g	h

After 5...Nc6, is 6.a3 a promising queenside attack, or just a loss of tempo?

An important theoretical decision for White is to choose whether to play a2–a3. While this move protects the b4 square and threatens the pawn advance b2–b4, it encourages Black's rook lift Ra8–a6–h6. As Lalic puts it:

It was not so long ago that 8.a3, with the obvious intention of expanding with b2–b4, was the standard move. However, after Black responds with the logical a7–a5, it became apparent in tournament practice that the inclusion of these moves is in fact in Black's favour, as it gives his queen's rook access into play via the a6-square.