The knight as a wrecking ball

When I was studying chess in my youth, I heard an interesting phrase that stuck in my mind: "the knight on 5th rank is worth an extra half a pawn". You want to know why? Because from there it can be easily sacrificed for a pawn! 

To explain this slightly paradoxical rule of thumb, let me show you a couple of games that feature the knight on f5, the star of all knights, and the sacrifice Nxg7, which can create havoc in the position of castled Black king.

We will begin with a game that was played two years ago by two amateurs in a tournament in Germany. The beauty of this game is that it showcases the main motives of this article in a pure form:

The scheme of development that we saw in this game is well-known and was used by many generations of chess players. In fact, a year ago I published one of my son's games that followed more or less the same scenario. 

However, it would be a mistake to think that this setup is only used by amateurs. In the next game we will see a Grandmaster follow the same template to quickly crush a FIDE Master in a rapid game:

As a word of precaution, I would like to point out that Nxg7 does not lead to win in ALL positions. After all, White sacrifices a piece for a pawn, so he better follows through and mate the king! In the following game it seems that Grandmaster either did not bother calculating the variations, or decided that his opponent was unlikely to find the best defense. That turned out to be correct, as Black quickly walked into a mate and thus missed a great chance to put the Grandmaster in a difficult situation!

I do not want the reader to get an impression that this motive is only relevant for Italian Game or Ruy Lopez pawn structures. The knight on f5 can be dangerous in almost every opening. To demonstrate this we will look at a game played by two leading Grandmasters in the most solid of all openings, the Petroff.

This game is a great testament to the tactical genius of Azerbaijani player Vugar Gashimov. That same year Gashimov reached his highest ranking, peaking as Number 6 on worldwide rating list in November 2009. Alas, five years later he passed away from an incurable illness. He was only 27 years old...

In conclusion, we will look at a game in which White managed to execute the same idea from a slightly different angle. The f5 square was firmly controlled by Black, so White knight approached the enemy via h5, sacrificed himself on the same square... It might sound that White simply did everything "by the book", but the follow-up to that sacrifice was far from standard!

Let us summarize what we learned in this article:

• "The knight on 5th rank is worth an extra half of pawn". This rule of thumb might sound silly, but it is often true!
• In Italian Game and Ruy Lopez White often sends his knight on a long journey: b1-d2-f1-g3-f5!
• Apart from controlling a lot of squares from his outpost on f5, the knight can sometimes act as a wrecking ball for the castled position of Black's king. As we have seen, Nxg7! could be both unexpected and very powerful!

• When one bishop is not enough (Lasker's double bishop sacrifce)
• The eternal bishop sacrifice (Bxh7+ sacrifice, part 2)
• The eternal bishop sacrifice (Bxh7+ sacrifice, part 1)
• Cavalry charge (Morphy's attacks, part 3)
• Kings and Epaulettes (Morphy's attacks, part 2)
• How to Beat Your Dad at Chess (Morphy's attacks, part 1)