The Carlsbad structure is as popular as ever. Even though the plans for how to play in it are well-known, modern practice continually introduces novel ideas. One of them, for example, is that the move …h6, known to be imprecise for a very long time, is in fact quite acceptable for Black.
Another idea, this time for White, was a refinement of Botvinnik’s plan known from the classical game Botvinnik-Keres, USSR Championship 1952.
In the following position, which arose in the recent game Vidit-Kryvoruchko, played at the European Club Cup in Austria in 2022, it was White’s turn to move.
We see that Black has played the move …h6, previously thought imprecise (because now Black cannot play the typical maneuver …Nf8-g6; however, Black has other ideas like …Nh5 now). White is ready to implement Botvinnik’s plan with Qc2, f3, and e4, but before doing any of that he played the very surprising move 11.a4!?
This is surprising because it kills off White’s other plan in this position; the minority attack on the queenside. However, White players have discovered two things: 1. Black’s plan to expand with …b5 and …a5 and then create play on the queenside is quite viable (as in the case of the immediate 11.f3 b5); and 2. Expanding on the queenside with a5 makes White’s centre expansion even stronger, plus it allows for the maneuver Nc1-b3-c5.
I am pretty sure that such a move would have never crossed Botvinnik’s mind.
In the game, Vidit implemented White’s strategy perfectly. He advanced the pawn all the way to a6 and then switched attention to the center and the kingside.
Here he played the move 20.g4!, further squeezing Black. Kryvoruchko didn’t want to stay passive with 20…Bc8 21.Nd3 when White can continue preparing the advance on the kingside, and lashed out with 20…Bxg4?! 21.fxg4 Nxg4, but after the precise 22.Bh3! Nxe3 23.Nd3 White was in control and won the game.
The move a4 has already been played by players like Caruana, Grischuk, Praggnanandhaa, Harikrishna and others will surely follow. The Carlsbad, in spite of being well-researched and the plans being known, doesn’t cease to surprise.