Mr. Perry's Theorytalk -- Mastering the Korchnoi Defense against the Closed Sicilian
The Korchnoi Defense is my weapon of choice as Black against the Closed Sicilian, beginning with the following move order:
Strategically, White encounters his first major choice here: He can either play f4, entering a Grand Prix style attack, g3, which will either resemble a calmer King's Indian attack or transpose into the f4 lines, or Nf3, switching back to an Open Sicilian. Of course there are other options, but these three seem to be the most popular. White's most accurate choice for maintaining an advantage is to transition to the Open Sicilian, resulting in a Taimanov or Kan Variation of the Sicilian Defense, and, from a personal standpoint, I already consider this a small victory because it heads into my familiar theoretical ground.
But since this blog post is on the Korchnoi defense, I'll be focusing mainly on the f4 and g3 lines, beginning with f4, the Grand Prix Attack.
White plays 3. f4 with the intention of building up a Kingside attack, and this leads into one of the strong reasons why I play the Korchnoi Defense. A key principal in chess is that when your opponent attacks the Kingside, you strike in the center, not only unraveling his attack, but creating a stronger one of your own, and the Korchnoi Defense performs this function wonderfully.
According to the Grandmaster database, Black's win ratio from this position is already a staggering 40-50%, and there are good reasons for this. The first is that, if Black plays correctly, White's Kingside attack is simply not going to happen, and the pushed pawns on the Kingside are going to leave the White King vulnerable. The second is that Black can gain the initiative from here, and it will become White, to his surprise, who's on the defensive.
However, it's now White who get's some say in what style of game is played from here on out, though all of them should be comfortable for Black, who has already obtained an equal position. That said, I see 4 broad ideas from which White can choose from:
1) Inviting d4
Black's plan here is straightforward: Control the center with his pieces and advance his Queenside pawns. This typically becomes a positional battle, but one which Black must welcome, since his threats on the Queenside will be so pressing that White will never have the time nor the pieces available to consider attacking the Black King.
2) Push the e5 pawn
When White pushes the e5 pawn, he recognizes that his Kingside attack isn't going to happen and instead simply locks it up, switching his focus to a head-on battle on the Queenside. However, his already exposed Kingside and reduced space on the Queenside will act as strategic weaknesses for the remainder of the game.
3) d4, The Strongest Choice
Despite being only the third most common move, d4 is White's best choice in this position and certainly the most dynamic. From here, it's actually Black who gets to decide the style of game that follows, a selection which simply depends on what kind of game he feels like playing. Responding with d5, he can follow with Nf6, inviting the e5 pawn push and entering an extremely closed position if this suits his tastes. Responding with d5, he can follow with dxe4, leading to a semi-closed position. Or, he can immediately reply cxd4, leading to a very open game with a distinctly Sicilian feel. White also has the option to take on d5 and castle Queenside, but this is a little better for Black. However, all of these options (as shown in the diagram) are solid and generally lead to equal positions with equal chances for both sides.
Note: One truly shocking fact about the move d4 is that, according to the database, 99% of Grandmasters (from a sample of 125 games) have played cxd4 in response, ignoring the also strong reply of d5! However, I believe this is because they did not know the theory behind the line I intend to show next, and thus feared it.
4) The Gambit.
When Black responds 5...d5 to 5. d4, as in the idea above, Black is actually offering a positional gambit, but one that, I'll argue, is both safe and powerful for Black:
Of all the variations I've seen in the Korchnoi Defense, this one is certainly the sharpest, and very difficult for White to figure out over the board. Although this variation is fairly uncommon, a player who wishes to respond 5...d5 must be familiar with it, and it does occur from time to time. In fact, I recently had a game with it, which ultimately inspired this blog post:
Here we'll conclude the use of the Korchnoi Defense against the f4 lines and now turn our attention to the also popular g3 lines.
This section will be much smaller than the one above because many of the lines can transpose into ones we've already covered, and so I'll be narrowing my focus on where things get different in the following variation:
From here, Black has two promising choices: The immediate 3...d5 or rather interesting 3...Nf6. The move Nc6 is also playable here, but after White puts his bishop on g2, Black is now unable to make the immediate d5 pawn break and will end up playing d6 instead; this position is still equal and fine, but seems to ignore the reason why Black played e6 in the first place and isn't what I'd consider being in the spirit of the Korchnoi Defense. So we'll cover the two options that, in my humble opinion, are the most promising for Black.
After 3...d5, the game could easily transpose into lines and ideas we've already covered, which I'll briefly illustrate:
The idea that's distinct from those already mentioned and is White's most accurate move in the position is the immediate 4. exd5.
This move has almost never been played by Grandmasters (only 30 games to my knowledge), but I will argue here that it is completely solid and will often lead to a game which ends in checkmate.
Needless to say, the above positions where Black has castled Queenside are tactical, with plenty of opportunity for mating attacks for both sides. And because 3...Nf6 has very little history, Black could play this move to take White out of his experience in the Closed Sicilian, while still playing something that is both solid and accurate.
Any player of the Sicilian Defense should have a basic opening repertoire, knowing what he's going to play either against the Open Sicilian or the Closed Sicilian (as well as perhaps the Alapin Sicilian). Personally, I consider the Korchnoi Defense of the Closed Sicilian as the counterpart to the Taimanov and Kan Variations of the Open Sicilian since it could at any time in the first few moves transpose into the latter, and a player could consider learning these related variations together. Conversely, the Korchnoi Defense might not be the right choice for players attached to the Najdorf Variation, who may want to learn the more common Fiancetto Variation as their weapon in the Closed Sicilian, since that too can similarly transpose.
I hope this sort-of guide to the Korchoi Defense has been enjoyable and instructive for all who took the time to read it. If you feel that I have overlooked any important lines, please do not hesitate to message me! I greatly enjoy discussing chess theory with strangers!