Chess Opening Theory/1. e4/1...c5/2. Nf3/2...Nc6/3. c3

Sicilian Defense: Delayed Alapin Variation
The Opening Line 1. e4 c5 2. Nf3 Nc6 can transform from the Old Sicilian to the Alapin variation with 3. c3. The ideas of this line are the same as the regular Alapin.

Common Responses
The common responses to 3. c3 are /3...Nf6/, /3...d5/ and 3...e6.

3...Nf6
The idea behind this move is to develop a knight, and strike at White's e4-pawn. Common replies to this move are 4. e5 attacking Black's knight and forcing it to move. The most common and best square to lace the knight is d5 with the move 4...Nd5. The knight on this square is now only subject to attack from the c4-pawn where if 5. c4?! Black can move the knight to b6, gaining an attack on the d-pawn and still controlling d5.

3...d5
This move provokes the center and Black demonstrates their wish to control the game. The move 3. d5 seeks to undermine the white pawn on e4 by trading it with Black's d-pawn. It also seeks to bring the queen out to the center where Black has chances to build huge center control. The move of 3. c3 prevents White's knight from coming out and attacking the queen, making it harder to expel the black queen from the center. By far the most common continuation after 3...d5 is 4. exd5 Qxd5. White has a few choices following the queen taking on d5. If White plays 5. d4 he enters the Sicilian Defense Alapin Variation, Barmen Defense. Black has many response but the best are developing a piece rather than the playable but slightly worse cxd4. Other responses to 3...d5 are d3 defending White's pawn as White seeks to maintain his stake of the center. Black's best responses to this are playing 4...e6 as Black also seeks to maintain his center. Another rare response is 4. e5?!, which Black can exploit by playing 4...Bg4.

3...e6
The pawn move of 3...e6 opens the diagonal for Black's bishop to protect the c5-pawn while preparing the push of d5. Common replies to 3...e6 are 4. d4 where Black responds with 4...d5 or the slightly worse 4...cxd5. The move 4...d5 keeps the tension in the center giving White the choice of opening the game and losing some control of the center. Common responses to the move 4...d5 are 5. e5 reaching the same position as the French Defense: Advanced, Paulsen Attack.