Right now I'm studying the blitz games of GM Danielsen for the second time. In this position he played Na3 à tempo with the following intrigueing comment: "if he takes on a3, he becomes weak on the black squares around his king."
White to move
This is all the more intrigueing, since usually he is the first to inflict his opponent with a double pawn with the words "I have won many, many games because of that double pawn"
Rybka would have played Na3 either.
This raises the question "how do you learn to get such positional ideas a tempo?". You can do tactical exercises till the cows come home, but this kind of ideas you will not learn. I have studied my own games, without ever getting the idea. I have studied master games without ever getting this idea.
This means that such ideas must be told by a grandmaster. There can't be no other way. Via a video, a book or a coach. Or maybe by solving positional problems with solutions checked by a GM.
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