@Irontiger: that is not very argumentative. I think f3 is a good move.
If black decides to withdraw his knight to f6 (d6 is not an option) loses he the pawn on g5 or is retreats white the bishop to f2 having a very strong centre after e4. Two good choices for white. Letting the pawn at g5 alive is not that bad choice, because there is no half open line on the king side of white. It will not advance quickly because of the pawn on f3. That are not viable options for black.
If you take a look at the position in the game, then has black this half open line and an isolated double pawn on the h-line and the bishop pair where white has a stronger centre and his knight can develop to his natural position. What more can you expect from a move that is normally in this position(with the white knight still on g1) akward? Here it is rock solid.
What is the alternative? 4. Bg3 giving black the opportunity to get the bishop pair?
4.Bg3 Nxg3 5.hxg3 gives Black the bishop pair indeed, but also an open h file to White and a solid pawn structure, when Black has weakened a bit with ...g5. Yes, it is roughly equal, and that's why I call the Trompovsky bad. 1.d4 d5 2.Bg5 is playable for a win, but 1.d4 Nf6 2.Bg5 does not offer much.
4.f3 (?) ends with the same loss of pair of bishop, but with weak pawns for White and the g file for Black. The center is killed after the game's ...e5, or ...d5 instead more weak-f6-square-friendly. The white f file is useless.
Neither the game variation, nor the line 4.Bg3, would give me any satisfaction if I were White. Maybe some players like it because of some reasons, but I have never heard those.
Some examples of these players are GM Igor Rausis, GM Igor Postny 2620+, GM Alexander Rustemov, GM Stellios Halkias, GM Daniel Campora and GM Julian Hodgson.
I think you are too conservative.White has got compensation for structural
damage, it`s easier for white to develop and black`s king is not entirely safe.The position is imbalanced and about equal.
What a game. It would be amazing to play a game like that. Na3 especially impressed me...
yes i agree f3 is a good move white doubles his pawns but builds a strong center which can be supported with the doubled pawns also to irontiger bg5 is not a bad move at all in fact its very good way of avoiding mainlines and playing a sharp variation
Added some beautiful lines