1. Main line 1. d4 d5 2. c4 dxc4 3. Nf3 Nf6 Choose a line 1. Main line 1. d4 d5 2. c4 dxc4 3. Nf3 Nf6 2. Mannheim Variation 1. d4 d5 2. c4 dxc4 3. Nf3 Nf6 4. Qa4+ Close 1. Main line 1. d4 d5 2. c4 dxc4 3. Nf3 Nf6 2. Mannheim Variation 1. d4 d5 2. c4 dxc4 3. Nf3 Nf6 4. Qa4+ Next