Two Knights Defence: free opening course

Key ideas

• Against 4.Ng5, block the bishop with 4...d5 at once. Moves like ...h6 come too late to save the f7 pawn.
• After 5.exd5, play 5...Na5 and chase the c4 bishop. Taking back with 5...Nxd5 invites the Fried Liver Attack.
• In the 4.Ng5 lines Black gives a pawn. In return Black develops fast and chases White's pieces with ...h6, ...e4 and ...Bd6.
• Against the quiet 4.d3, develop calmly with ...Be7, ...O-O and ...d6. Then gain space on the queenside with ...Na5, ...a6 and ...b5.
• Watch for loose pieces. White's knights on e5 and e4 often have no pawn to protect them, and one careless recapture can drop a piece.

The 6 variations in the course

• 4.Ng5 d5 5.exd5 Na5: main line: 1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6 4. Ng5 d5 5. exd5 Na5 6. Bb5+ c6 … — White attacks f7 with 4.Ng5. Black blocks with 4...d5 and, after 5.exd5, gives a pawn with 5...Na5. Black chases White's pieces with ...c6, ...h6, ...e4 and ...Bd6, and gets active play for the pawn.
• 4.Ng5 main line: 10.f4: 1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6 4. Ng5 d5 5. exd5 Na5 6. Bb5+ c6 … — White supports the e5 knight with the f-pawn. Black takes en passant, opens the f-file and castles. White's king is still in the middle, and Black has strong play for the pawn.
• 4.d3: the quiet Italian: 1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6 4. d3 Be7 5. O-O O-O 6. Re1 d6 … — White avoids sharp play with 4.d3. Black develops calmly, castles, and then gains queenside space with ...Na5, ...a6, ...b5 and ...c5. It is a slow game where good plans matter more than tactics.
• 4.d4 exd4 5.O-O: back to the centre: 1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6 4. d4 exd4 5. O-O Nxe4 6. Re1 d5 … — White opens the centre and castles, giving a pawn. Black takes on e4, then gives the piece back with ...d5. The queen steps to a5 with a pin, Black castles long, and the game is balanced.
• 4.d4 exd4 5.e5: 1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6 4. d4 exd4 5. e5 d5 6. Bb5 Ne4 … — White pushes 5.e5 to chase the f6 knight. Black answers in the centre with 5...d5 and puts the knight on e4. After the trade on c6 Black has the two bishops and an easy game.
• 4.Nc3: the fork trick: 1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6 4. Nc3 Nxe4 5. Nxe4 d5 6. Bd3 dxe4 … — Against 4.Nc3 Black can take on e4 at once. After 5.Nxe4 d5 a pawn fork wins the piece back. Black gets the two bishops and an equal, open game.

Traps you will learn (3)

• Fried Liver Attack: 5...Nxd5? 6.Nxf7 — After 4.Ng5 d5 5.exd5, taking back with 5...Nxd5 is risky. White gives the knight on f7, drags Black's king into the centre and attacks the pinned d5 knight. This is why the main line is 5...Na5.
• 4...h6? 5.Nxf7: the fork on f7 — Against 4.Ng5 the move 4...h6 looks natural, but it does nothing for f7. 5.Nxf7 forks the queen and the h8 rook, and White wins the rook.
• 11.Bxd3?? Bxe5: the loose knight — In the 4.Ng5 main line White must take back on d3 with the knight. Taking with the bishop leaves the e5 knight without a guard, and Black wins it.

How the opening courses work

Each course teaches an opening in a few main variations. For every move you read why it is played, which other moves are good, and which tempting moves are mistakes and why. Each course also shows the traps of the opening: the ones you can set and the ones to avoid.

After a lesson you play the moves yourself in a drill. The lines you learn go into your review, which brings them back when you are about to forget them (spaced repetition). 30 line courses add many short lines per opening, a few new ones a day, and every named opening, more than 3,800 lines, has a lesson of its own.