Capturing with the pawn is equally popular.
1. e2e4  1... c7c5  2. g1f3  2... b8c6  3. f1b5  3... e7e6  4. c2c3 A rare move, compared to the more popular 4.0-0 or 4.Bxc6. 4... d7d5 A critical reply. 5. e4d5 