Originally posted by AThousandYoung
Let's talk about Game 4725925.
To start, why does Black play 6...Nbd7? I'm never certain what the best move is on move 6 when I play this line.
hi, please note that this is not a commentatry on the aforementionad game but it answers your question with some theory added in, so
idea behind 6...Nbd7, mmm, the main line leading to this is as follows, 1.d4 Nf6, 2.c4 g6, 3.Nc3 Bg7, 4.e4 d6, 5.Nf3 0-0, 6.Be2 and our move 6. ..Nbd7 which although the knight gets in the way of the c8 bishop this is not needed at present,( the main alternative of course being 6...e5)
moving the knight to d7 is an attempt to avoid the passivity that the knight may suffer later after other main line continuations, for example, 6...e5, 7.0-0 Nc6, 8.d5 Ne7 and it also takes away whites option to trade queens early, for example 6. ..e5 7.dxe5 dxe5, 8.Qxd8 Rxd8. further to this after 6. ..Nbd7 white castles
7.0-0 black now has a free hand to go about seeking counterplay, so blacks response, 7. ..e5, black strikes back at the white centre.
8.Qc2, is a versatile move, white protects e4 and vacates the d1 square for whites rook, which may be crucial later on, blacks reply 8. ..Qe7, an unsual move which leads to similar positions in other main lines, for example a popular alternative is 8. ..c6, when after white plays 9.Rd1 black moves the royal lady to e7 anyhow. trading centre pawns with 8 ..dxe4, 9.Nxd4 would give white more space and a greater pawn presence in the centre, however black could use the open e-file, the long diagonal a1-h8 and the c5 square, a popular continuation would be 9. ..Re8, 10.Rd1 c6. you also might like to consider 8. ..Nh5 threatening to win whites d-pawn, following 9.Rd1 ..Nf4, 10.Bf1 c5, 11.dxe5 dxe5 play would be unclear.
9.Rd1, white gives d4 pawn more protection, black plays 9. ..c6, flexible move which stops white entertaining any idea of play Nd5 next
10.d5 advances in the centre and takes away the option for black taking on d4 at present. if white plays 10. Rb1 instead, black has done well with 10...exd4, 11.Nxd4 Nc5, 12.f3 a5., blacks reply after 10.d5 is to close the centre with 10...c5, this takes play to the wings where whites rook placed on d1 will be less influential to support any kingside play for white and it also slows down whites queenside advance.
11.Bg5 which gets last minor piece developed and stops blacks counter play with ..Ne8 with pawn advance f7-f5 coming next. blacks response 11...h6 attacks the bishop and prepares to make progress on the kingside.
12.Bh4 keeps up the pin, blacks response 12. ..g5, which appears to weaken blacks pawn structure but breaks the pin on the f6 knight, this is a committing move but black will be unable to have a pawn on f5 for the duration of the game, white would simply trade and use e4 for his pieces.
13.Bg3 only reasonable move. blacks response, 13. ..Nh5 moves the knight to an aggressive post eyeing the bishop and the f4 square.
14.Nd2 attacks h5 knight and post knight to typical square in these type of positions, black must make strategic decision now, 14 ..Nf4, much better than taking the bishop, as after 14..Nxg3?!, 15.fxg3 Nb6, 16.Bd3, white would have full control over f5 square.
15.Nf1 trying to get the knight to e3 to get control of important f5 square, blacks response 15...Nf6, gets horsey closer to kingside action and opens the diagonal for white squared bishop, and although it gets in the way of the f7 pawn this will not be long term.
16.Ne3 completes the three move manoeuvre of the knight from f3 to e3 controlling f5 square, blacks response, 16...Nxe4! which removes a centre pawn and will get rid of the ugly hole on f5, based on tactical combination black will be able to regain the sacrificed piece.
I am no expert myself and just a learning player like yourself, so hope fully this helps your understanding a little better - regards Robbie.