What's the accurate move order for this line?

Question

[FEN ""]
1.e4 g6 2.d4 Bg7 3.Nc3 c6 4.f4 d5 (4...Qb6 5.Nf3 d5 6.e5 Bg4 7.Be2) 5.e5 Qb6

According to the Lichess Masters database, both 4...Qb6 and 4...d5 5.e5 Qb6 are sidelines for Black that score quite well. Which is the more accurate move order here?

To me, it seems like 4...Qb6 is better / more forcing since it comes with a double attack on the d-pawn, forcing White to play 5.Nf3 and giving our light-squared bishop a clear path to develop on g4. (5.e5 seems premature to me-- we haven't committed our d-pawn, so we can start undermining the center with 5...d6.) On the other hand, I don't really see the point of 4...d5 5.e5 Qb6-- White can play pretty much anything he wants for his 6th move, ie. he can question your queen immediately with 6.Na4 and then consolidate his pawn chain with c3, or make it harder for our bishop to develop with 6.h3. Is my intuition that 4...Qb6 is better correct?

Answer 1

Most likely 4...d5 is a little bit better. Why do you want your queen to b6 at all? Usually developing the queen early in the opening is not recommended (for various different reasons) and I think this is no exception. Queen is offsides on b6. It's premature developing, you don't yet know where the queen belongs. After 4...d5 5.e5, the most common moves for Black are 5...h5 and 5...Nh6. It seems 5...h5 has been more popular lately (at least in my database) and I have to say that I personally like it more as well. Pawn to h3 would be a positional mistake by White. White most likely will (and should) develop his knight to f3 during the next few moves after which Black can play Bg4.

Anyway, both moves (4...Qb6 and 4...d5) are definitely playable. I think you should vary your openings and use both, even though I believe 4...d5 to be theoretically slightly better (and more in accordance with the chess principles).

Answer 2

I found an explanation of this move in Jon Speelman's Modern Defence book (published 2000):

So my intuition was correct; 4...Qb6 does seem to be the more accurate move.