I hope it's OK with a question on the fringes of existing opening theory.

If white wants to combine pawn moves f4 and b4 early in the opening, he has to be aware of the possibility of black snatching a pawn. One example is Larsen-Raizman from the 1958 Olympiad 1.f4 Nf6 2.Nf3 g6 3.b4, where black could have gone 3...Nd5!? with complicated play.

Even earlier possible pawn losses are 1.f4 d5 2.b4 Qd6 and 1.f4 Nf6 2.b4 Nd5. I want to focus on this last variation.

    [FEN ""]
1.f4 Nf6 2.b4 Nd5

Before I thought this was good for black, but now I'm not so sure anymore. 3.e4 Nxf4 4.d4 looks like great compensation, although ironically I would prefer the b4 pawn back on b2. Black is better advised to play 3...Nxb4, for instance 4.d4 d5. A possible improvement for white is 3.d4 and after 3...Nxb4 start chasing the knight around.


Is 2...Nd5 advisable for black?

How should white react?

  • 2
    Once you are into analysing weird variations: After 1.f4 Nf6 2.b4 Nd5 3.d4 perhaps 3...Nf6 might be playable. The plan is simply 4...d5 and soon Bf5 (or Bg4). Talk about flaunting all the rules :) ( By the way; Hei, Dag! Lenge siden sist :) )
    – Halvard
    Aug 2, 2013 at 17:14
  • Speaking of moving the same piece in the opening: I once had a game 1.e4 Nf6 2.e5 Nd5 3.c4 Nb6 4.a4 a5 5.c5 Nd5 6.Nc3 Nb4 with a great position. Five knight moves and a5, I wonder if there are any rules for that kind of opening play :) Aug 3, 2013 at 19:56

4 Answers 4


This question led me to spend two hours of my life looking at a line that I most likely never will get to play. I went into it being quite confident that Nd5 was a bad move simply because White would get too much development for the cost of a simple pawn. Analysing back and forth with Houdini has nevertheless convinced me that Nd5 is perfectly playable.

The similarities to the Sokolsky Opening

To get a feel for the b4 pawn it helps to understand a variation from the Sokolsky Opening. It goes like this:

[FEN ""]

1. b4 e6  2. Bb2 Nf6  3.b5

Here the pawn on b5 is slightly annoying. It cannot be easily removed as a6 can be answered by a4 (it does not matter if the rooks are swapped off as White intends to castle short anyway) and c6 can be answered by e3 when Black must take away from the centre to remove the pawn.

In the game, however, Black can simply play a6 in the similar position as White can't answer with a4:

[FEN ""]

1.f4 Nf6  2. b4 e6  3.b5 a6

So after 2...e6 White is only left with 3 a3, which, although reasonable, is another pawn move on the wing. Black will be very solid after playing simple development like d5, Bd6 and 0-0. This is slightly better than one of the main lines of the Sokolsky Opening, which is not that good to start with (but where White often ends up playing f4 later).

Houdini 3 on 2...Nd5

The currently strongest engine on the planet is Houdini 3. When you let it analyse the position before 2...Nd5 to a depth of 25 it likes 2...d6 (claiming a small advantage for Black) the best (with 2...d5 as a strong second). 2...Nd5 does not come up as a top five alternative. Houdini is initially not impressed by grabbing the pawn.

White plays 3 e4

Nevertheless, 2...Nd5 is still an interesting alternative and certainly gives more entertaining variations to look at. First let us take a look at what happens if White plays 3 e4 after 2...Nd5 and then Black takes the pawn at b4:

[FEN ""]

1.f4 Nf6  2.b4 Nd5  3.e4 Nxb4  4.c3 N4c6  5.d4 d5  6.Nd2 dxe4  7.Nxe4

To explain this variation it is important to know that Black's hope and main idea against a setup with f4-e4-d4 is to play d5 and develop Bc8 to f5or g4. In the variation above it turns out Black can't play either. Bg4 simply hangs the bishop and Bf5 runs into Ng3 chasing it back. Here I (and Houdini) believe White has compensation for the pawn (although perhaps nothing more).

So, let us look at the alternative. Initially I was sure that 3...Nxf4 must be horrible for Black, but it turns out it is good after 4. d4 e5!:

[FEN ""]

1.f4 Nf6 2.b4 Nd5 3.e4 Nxf4 4.d4 e5 5.dxe5 Ne6

As seen above, if White makes the natural capture on e5, Black just retreats the knight. Material is now even, but Black has two threats; The killing Qh4+ and just grabbing the b4 pawn. So Black will end up a pawn up with a much better pawn structure and no imminent attack from White.

Instead White must play:

[FEN ""]

1.f4 Nf6 2.b4 Nd5 3.e4 Nxf4 4.d4 e5 5.Nf3 Ne6 6.d5 Nd4 7.c3 (7.Ng5) Nxf3+ 8.Qxf3 a5

In the above variation please note that 6 Nxe5 runs into 6...Qxh4+. The same idea works against 7 Nxd4. And despite all the knight moves Black is left clearly better in this variation too. If you want to play this variation with White you need to try the chaotic 7.Ng5!?, hoping to trap the knight at d4. Have fun analysing that.

White plays 3 d4

I believe 3 d4 is a strong alternative for White. If Black takes the pawn on b4 it transposes to a variation we have already looked at:

[FEN ""]

1.f4 Nf6 2.b4 Nd5 3.d4 Nxb4 4.c3 N4c6 5.e4 d5 6.Nd2 dxe4 7.Nxe4

So, as I mentioned in a comment to the question, perhaps Black can try the amazing 3...Nf6 with the simple plan of d5 and Bf5. In this variation White will have more space, but also more weaknesses (and, no, Black is not behind in development):

[FEN ""]

1.f4 Nf6 2.b4 Nd5 3.d4 Nf6

White plays 3 Bb2

Seeing that White will lose one pawn anyway, why not play a development move like and see which pawn Black decides to take? It seems that Black can just grab the f4 pawn and get away with it. Let us see what happens if White tries to push Black off the board:

[FEN ""]

1.f4 Nf6 2.b4 Nd5 3.Bb2 Nxf4 4.e3 Ng6 5.h4 h5 6.Be2 d5 7.Bxh5 Qd6

White won the h5 pawn, but now the threat of Qg3+ is just killing White. Instead, if White tried some quiet development moves:

[FEN ""]

1.f4 Nf6 2.b4 Nd5 3.Bb2 Nxf4 4.e3 Ng6 5.Nf3 e5 6.Nxe5 Nxe5 7.Bxe5 Nc6

Black gets a small advantage by the precise 5...e5 which trades the not so optimally placed Ng6 (Black is still a pawn up). Note that the alternative 3 Nf3 could easily transpose as it does not seem that White can improve much


The fork 2...Nd5 works out well for Black, despite Houdini's initial reluctance towards it. It seems White should play 3 d4 to equalise. I would certainly try 2...Nd5 should 1 f4 Nf6 2 b4 be played against me.

  • Great, Halvard! This was more than I hoped for. One small question: In the 1.f4 Nf6 2.b4 Nd5 3.d4 Nxb4 4.c3 N4c6 variation, what do you think about 5.d5? Aug 3, 2013 at 19:16
  • I would also add that 1.f4 Nf6 2.b4 Nd5 3.d4 Nxb4 4.a3 looks interesting, with the follow-up 4...Nc6 5.d5 Na5 and later Bb2. Aug 3, 2013 at 19:32
  • @DagOskarMadsen This was more than I planned to answer originally :) Of your two variations I think the 4.a3-variation feels more natural (as a future Bb2 just must be good). It is certainly an interesting alternative to the variation I mentioned. More chaos, if you like that.
    – Halvard
    Aug 3, 2013 at 20:46

I think this depends on how you play chess as a human and how good the players are. Some people want to take every pawn they can and then they are defending their king, swapping pieces and then they win the game in the end game. Some want to give them away for some initiative (like white in our example). I think an engine will definitely play Nd5 and grab the pawn(s).

I would play Nd5 and take b4 instead of f4, because white gets aggressive play after e4 Nxf4 d4, especially the half open f file is very nice.

If white plays c3 after Nd5, I would take f4.


F4 is a reasonable opening move, to discourage Black's e5. He played Nf6 in a similar vein to discourage your e4.

But the followup move, b4, was bad. Not only does it allow the knight fork, but it has no relation to f4. (The fork is really the symptom, and not the disease). Most logically, you might follow with another move on the kingside such as Nf3 or g3. If you want to play on the queen side, the logical moves are Nc3, or d3, both of which would protect a future pawn on e4 from the knight on f6.

  • Yes, I agree the b4 move is a bit random. In the Larsen game it makes more sense, to counter black's fianchetto with a bishop on b2. Aug 3, 2013 at 19:25
  • Not entirely true. f4 and b3 are commonly paired to control e5. Playing b4 instead of b3 allows a later b5, controlling c6 where a BN would contest e5. There is at least a little method in the madness.
    – Philip Roe
    Apr 24, 2018 at 1:11

What white is doing doesn't make any sense, it's violating the simple rules of chess: dominating the center.

Nd5 isn't too bad, but the fork is bad i believe

    [FEN ""]
1.f4 Nf6 2.b4 Nd5 d3 Nxb4 Bd2

The knight is lost, if he's gonna retreat, white could start developing his peaces, and black is down in development.

  • -1 For three reasons: 1: Domination the centre is not a rule, it is more like good practice or a guideline (but I do get your point) 2: Nd5 is the fork (meaning if Nd5isn't too bad then neither is the fork) 3: The knight is certainly not lost.
    – Halvard
    Aug 3, 2013 at 16:57
  • @Halvard the knight has to retreat, by doing so, black will give white more advantage, white has 1 move advantage in any game, why give him more and more? if black decided to defend the knight on d5 square by a5 then c3 and now it's lost... lets take another position where black do c5 instead white respond c3 i dont think that the black queen could do anything, the knight will be lost if he doesn't retreat as i indicated in my answer, unless you have another line
    – Lynob
    Aug 3, 2013 at 17:30
  • The knight is not lost. It can retreat to either a6 or c6 without giving White any more tempi for developing. Even after 4...a5 5.c3 the knight can still retreat to a6 or to c6. It is not worth giving up the knight for just one tempo. After 4...N4c6 Black should be perfectly fine (and ready for an imminent d5).
    – Halvard
    Aug 3, 2013 at 19:05

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