Chess Opening Theory/1. e4/1...e5/2. Nf3/2...Nc6/3. Bc4/3...Nf6/4. d4/4...exd4/5. O-O/5...Nxe4/6. Nc3/6...dxc3/7. Bxf7/7...Kxf7/8. Qd5/8...Ke8

= Nakhmanson Gambit, Ke8 Defence =

8...Ke8
The immediate 9.Qxe4+ would be a blunder allowing the Black queen to start  chasing the White one around threatening to trade.

But since the e4-knight has to be captured before it retreats to f6, the only move here is 9. Re1.