1. e2e4  1... c7c6  2. d2d4  2... d7d5  3. b1c3  3... d5e4  4. c3e4 This was once the undisputed main line of the Caro-Kann Defense. Nowadays the advance variation (4.e5) is also very popular. 4... g8f6 The fashionable move, supplanting 4...Bf5 and 4...Nd7.