Cochrane Gambit

The opening moves of the Cochrane Gambit are as follows:

1.e4 e5
2.Nf3 Nf6 (Black plays the Petroff Defense, a highly solid (and dull) variation.
3.Nxe5 d6
4.Nxf7!?

This bizarre-looking gambit is thought to be highly unsound, and is almost never seen at high-level chess tournaments. White sacrifices a piece on the fourth move in return for two pawns and the opportunity to displace Black's king and deprive him of the right to castle. However, it is generally considered that White's compensation is insufficient for the sacrificed material. A typical continuation would be:

4...Kxf7
5.d4 g6
6.Nc3 Bg7 (6...Qe8 is recommended as better for Black)
7.Bc4+ Be6
8.Bxe6+ Kxe6
9.f4 Kf7
10.e5 Ne8
11.Qf3 c6
12.Ne4 with good attacking chances for White.

The reputed unsoundness of the gambit made it all the more surprising when GM Veselin Topalov played it against no less a player than Vladimir Kramnik in the Linares supertournament in 1999. Kramnik was not yet world champion, but already had a fearsome reputation, and most people were of the opinion that he would defeat Garry Kasparov one day. In addition, Linares is the strongest tournament of the annual chess calendar, about as high-profile as you can get without being a world championship match. For Topalov to play the Cochrane Gambit at this level was a huge risk, and what was even more surprising was that he drew, and almost won, the game.