Chess Opening Theory/1. e4/1...e5/2. Nf3/2...d6/3. d4/3...Nd7/4. Bc4/4...Ngf6/5. dxe5/5...Nxe5

5...Nxe5
This is the most testing move, though it also loses. Black sees that dxe5 is splattered by 6.Ng5, when f7 is defenseless.

The only winning move is 6.Nxe5.