A04-A42 (+B06-B27)

Modern Defense

39 named lines in this family, ECO A04-A42 (+B06-B27). Under each line you get its moves and the sentences it adds that this page has not already printed. A line's own page carries up to its first 4 per-move notes in full.

Semi-Averbakh Variation, Polish VariationA04

1. Nf3 c5 2. c4 g6 3. d4 Bg7 4. e4 Qb6

Black's kingside bishop takes the long diagonal. ...g6 before anything: maximum flexibility, the g7 bishop as the anchor, and the pawn breaks chosen only after White commits.

• 1. Nf3 Develops the knight to f3, eyeing d4 and e5. Theory calls this the Zukertort Opening.
• 1... c5 Fights for d4 from the flank - contesting the centre without committing a centre pawn. Theory calls this the Sicilian Invitation.
• 2. c4 Fights for d5 from the flank - contesting the centre without committing a centre pawn. Theory calls this the Symmetrical Variation.
• 2... g6 Prepares the fianchetto: the bishop will take the long diagonal via g7.

Semi-Averbakh Variation, Pterodactyl VariationA04

1. Nf3 c5 2. c4 g6 3. d4 Bg7 4. e4 Qa5+

Semi-Averbakh Variation, Pterodactyl Variation AcceptedA04

1. Nf3 g6 2. d4 Bg7 3. e4 d6 4. c4 c5 5. dxc5 Qa5+

An early pawn trade leaves the c-file as Black's avenue and the d-file as White's - both sides get real winning chances down their own file. White is up material out of the opening - Black is banking on activity to show for it.

• 1... g6 Theory calls this the Kingside Fianchetto.
• 2. d4 Stakes a claim in the centre, controlling e5, and frees the bishop and queen.
• 2... Bg7 Fianchettoes the bishop onto the long diagonal, pressuring d4 and e5 from a distance.

Lizard Defense, Pirc-Diemer GambitA40

1. d4 g6 2. h4 Nf6 3. h5

• 1... g6 Theory calls this the Modern Defense.
• 2. h4 A useful waiting move that grabs space on the h-file.
• 2... Nf6 Develops the knight to f6, eyeing d5 and e4.

Beefeater VariationA40

1. d4 g6 2. c4 Bg7 3. Nc3 c5 4. d5 Bxc3+ 5. bxc3 f5

The structure hands White the half-open b-file - rook pressure down it is a standing plan.

Main line, after 1. d4, through 3... d6A41

1. d4 g6 2. c4 Bg7 3. Nc3 d6

Neo-Modern DefenseA41

1. d4 g6 2. c4 Bg7 3. e4 e5

The pawns on d4 and e5 stand in direct tension - the first player to resolve it chooses the structure.

Averbakh SystemA42

1. d4 g6 2. c4 Bg7 3. Nc3 d6 4. e4

Kotov VariationA42

1. d4 g6 2. c4 Bg7 3. Nc3 d6 4. e4 Nc6

Randspringer VariationA42

1. d4 g6 2. c4 Bg7 3. Nc3 d6 4. e4 f5

Averbakh Variation, Pseudo-SämischA42

1. d4 g6 2. c4 Bg7 3. e4 d6 4. Be3 Nf6 5. f3

Main line, after 1. e4, through 1... g6B06

1. e4 g6

• 1. e4 Stakes a claim in the centre, controlling d5, and frees the bishop and queen.

Fianchetto GambitB06

1. e4 g6 2. d4 f5

• 2... f5 Challenges the pawn on e4 - the central tension has to resolve. Theory calls this the Fianchetto Gambit.

Main line, after 1. e4, through 2... Bg7B06

1. e4 g6 2. d4 Bg7

Norwegian DefenseB06

1. e4 g6 2. d4 Nf6

• 2... Nf6 Theory calls this the Norwegian Defense.

Bishop AttackB06

1. e4 g6 2. d4 Bg7 3. Bc4

Standard LineB06

1. e4 g6 2. d4 Bg7 3. Nc3

Three Pawns AttackB06

1. e4 g6 2. d4 Bg7 3. f4

Westermann GambitB06

1. e4 g6 2. d4 Bg7 3. Bd2

Wind GambitB06

1. e4 g6 2. d4 Bg7 3. Bd3

Bishop Attack, Bücker GambitB06

1. e4 g6 2. d4 Bg7 3. Bc4 b5

Lizard Defense, Mittenberger GambitB06

1. e4 g6 2. d4 Bg7 3. Nc3 d5

The pawns on d5 and e4 stand in direct tension - the first player to resolve it chooses the structure.

Modern PterodactylB06

1. e4 g6 2. d4 Bg7 3. Nc3 c5

Mongredien Defense, with Nc3B06

1. e4 g6 2. d4 Bg7 3. Nc3 b6

Mongredien Defense, with Nf3B06

1. e4 g6 2. d4 Bg7 3. Nf3 b6

Standard DefenseB06

1. e4 g6 2. d4 Bg7 3. Nc3 d6

Pseudo-Austrian AttackB06

1. e4 g6 2. d4 Bg7 3. Nc3 d6 4. f4

Two Knights VariationB06

1. e4 g6 2. d4 Bg7 3. Nc3 d6 4. Nf3

Bishop Attack, Monkey's BumB06

1. e4 g6 2. Bc4 Bg7 3. Qf3 e6 4. d4 Bxd4

The structure hands White the half-open d-file - rook pressure down it is a standing plan. Black comes out ahead on material - White needs concrete play to justify it.

• 2. Bc4 Develops the bishop to c4, eyeing d5. It eyes f7, the one square only the king defends.

Norwegian Defense, Norwegian GambitB06

1. e4 g6 2. d4 Nf6 3. e5 Nh5 4. Be2 d6

Two Knights Variation, Suttles VariationB06

1. e4 g6 2. d4 Bg7 3. Nc3 c6 4. Nf3 d6

Anti-ModernB06

1. e4 g6 2. d4 Bg7 3. Nc3 c6 4. Bc4 d6 5. Qe2

Dunworthy VariationB06

1. e4 g6 2. d4 Bg7 3. c4 d5 4. exd5 c6 5. dxc6 Bxd4

An early pawn trade leaves the c-file as Black's avenue and the e-file as White's - both sides get real winning chances down their own file.

Gurgenidze DefenseB06

1. e4 g6 2. d4 Bg7 3. Nc3 c6 4. f4 d5 5. e5 h5

Masur GambitB06

1. e4 g6 2. d4 Nh6 3. Nc3 f5 4. Bxh6 Bxh6 5. exf5 O-O

An early pawn trade leaves the e-file as White's avenue and the f-file as Black's - both sides get real winning chances down their own file.

• 2... Nh6 Develops the knight to h6. It backs up the pawn on f7.

Semi-Averbakh Variation, Pterodactyl Variation DeclinedB06

1. e4 g6 2. d4 Bg7 3. c4 c5 4. Nf3 d6 5. Be2 Qa5+

Two Knights Variation, Suttles Variation, Tal GambitB06

1. e4 g6 2. d4 Bg7 3. Nc3 d6 4. Nf3 c6 5. Bg5 Qb6 6. Qd2 Qxb2

Black keeps the extra pawn; White plays for time, open lines, and initiative - the classic gambit trade.

Geller's SystemB07

1. e4 g6 2. d4 Bg7 3. Nf3 d6 4. c3

Pterodactyl VariationB27

1. e4 c5 2. Nf3 g6 3. d4 Bg7 4. Nc3 Qa5

White's knight on c3 is pinned against the king.

• 1... c5 Theory calls this the Sicilian Defense.
• 2... g6 Theory calls this the Hyperaccelerated Dragon.

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