Chess Opening Theory/1. d4/1...d5/2. c4/2...c6/3. Nc3/3...dxc4/4. e3/4...b5/5. Nxb5/5...cxb5/6. Qf3/6...Nc6/7. Qxc6/7...Bd7/8. Qf3/8...e5

8...e5!
This excellent pawn sacrifice completely frees black's position. With the Bishop threatening coming to b4, and the queen exposed on f3, black has a crushing initiative. What if dxe5? Well, then the d-file open, and Black's attack accelerates. Check the theory table for more info about what happens after dxe5. White's best is probably Bd2, stopping Bb4 and holding life and limb together.