1. e2e4  1... e7e5  2. g1f3  2... b8c6  3. f1b5  3... g8f6  4. e1g1  4... f6e4  5. f1e1  5... e4d6  6. a2a4 Carlsen has many small weapons he successfully employs to create practical problems against the solid Berlin Defense. 6... f8e7 