The rook now supports a knight move to e5 and also allows the Nd2-f1-g3 maneuver.
1. e2e4  1... c7c6  2. d2d4  2... d7d5  3. e4d5  3... c6d5  4. f1d3  4... b8c6  5. c2c3  5... e7e6 This is historically not a very popular move. Usually, Black tries to develop the c8-bishop before playing e6. This move, however, was played by Carlsen and Caruana, among others. 6. c1f4  6... f8d6  7. f4d6  7... d8d6  8. g1f3  8... g8e7  9. e1g1  9... e8g8 The pawn structure resembles the London System.