why was g4 a inacuracy ?

[Event "rated rapid game"] [Site "https://lichess.org/AxsjGMpR"] [Date "2026.09.24"] [Black "PJAVG"] [Variant "Standard"] [TimeControl "900+10"] [Annotator "lichess.org"] 1 e4 c5 2 Nf3 Nc6 3 d4 cxd4 4 Nxd4 e5 5 Nb3 Nf6 6 Nc3 Be7 7 f3 O-O 8 Be3 d6 9 Qd2 h6 10 O-O-O a5 11 Kb1 a4 12 Nc1 a3 13 b3 Be6 14 g4?! (0.73 --> -0.13) Inaccuracy. Nd5 was best. (14 Nd5 Bxd5 15 exd5 Nd4 16 c3 Nf5 17 Bf2 h5 18 Bb5 Ne8 19 Ne2 Nh4)
14...d5?? (-0.13 --> 4.41) Blunder. Nd4 was best. (14...Nd4 15 Bxd4 exd4 16 N3e2 d5 17 e5 Nd7 18 Nd3 Qc7 19 f4 Bxg4 20 Rg1) ...

Don't you think that the position after 14 Nd5 looks better for White than the position after 14 g4 Nd4 ?

@najdorfplayer48 said ^

https://lichess.org/AxsjGMpR

It's an inaccuracy because Nd5 is a better move, making the knight very strong. If they capture your knight with their knight, you recapture back and fork their knight and bishop. If they capture with their bishop, you recapture back and they lose the bishop pair.

It's an inaccuracy because Nd5 is a better move, making the knight very strong. If they capture your knight with their knight, you recapture back and fork their knight and bishop. If they capture with their bishop, you recapture back and they lose the bishop pair.

why is losing the bishop pair bad ?

@najdorfplayer48 said ^

It's an inaccuracy because Nd5 is a better move, making the knight very strong. If they capture your knight with their knight, you recapture back and fork their knight and bishop. If they capture with their bishop, you recapture back and they lose the bishop pair.

why is losing the bishop pair bad ?

Because generally bishops are better than knights in endgames.

Check this blog: https://lichess.org/@/The_Knightmare_Bro/blog/the-power-of-the-bishop-pair/hwJtGOEF

14 g4? is a mistake. It holds no real threat, and the centralization 14...Nd4 holds for black.
14 Nd5 would give white a solid advantage.

@tpr said ^

14 g4? is a mistake. It holds no real threat, and the centralization 14...Nd4 holds for black.
14 Nd5 would give white a solid advantage.

i understand now that the knight move is better but why has g4 no thread ? it could open a file in the future

@najdorfplayer48 said in #4:

... why is losing the bishop pair bad ?

“... [Part of Masters of the Chessboard by Richard Réti] can be appreciated as almost a primer on the subject of how to turn the two bishops into a significant advantage. ...” - GM Andy Soltis (2011)
https://www.amazon.com/dp/092389148X?lv=shuf&channelId=500&plpRedirect=mhFallback&asin=B006ZQISDY&revisionId=f4836601&format=3&depth=1

@najdorfplayer48 said in #7:

... but why has g4 no thread ? it could open a file in the future

How would you have reacted after 14 g4 Nd4 ?

The problem with g4 is that the knight on c6 can jump to d4, attacking f3 that is no longer defended after g4.
If the black knight were at b6 or d7, then g4 would be viable.
The problem of Nc6 is that white's move Nd5 gains strength, as Nd5 Nxd5 exd5 forks Be6 and Nc6.
If the black knight were at b6 or d7, then Nd5 would not be as strong.

The problem with the bishops is that Be6 is black's good bishop: not on the color of its pawns, and Be7 is black's bad bishop, on the color of its pawns d6 and e5. So Nd5 Bxd5 is good for white.
Likewise Be3 is white's good bishop, not on the color of its pawns, and Bf1 is white's bad bishop, on the color of its pawns e4, f3. So g4 Nd4 Bxd4 is good for black.