1. e4 g6 2. d4 Bg7 3. Be3 c5 4. c3 cxd4 5. Bxd4?! (I'm black)

How would black best deal with this unorthodox approach to the modern? The one game in my database with this opening has a master class player play 5...f6 which looks extremely awkward to me, and I refuse to believe such a opening by white can cause this much of a concession.

The way I've been dealing with it has been: 5... Nf6 6. e5 Nd5 7. Bxa7 Nxc3 8. Nxc3 Rxa7 but I'm still not convinced whether this is good for black or if I missed something beforehand.

help?

Your move order posted is not correct...1.e4 , g6 2. Bg7 , d4...

You need the book by Lev Albert,"The Pirc Alert!"  This will show you the similarities between the "Modern and the Dragon and the Phillidor and several other modern type defences!!"

The biggest thing is when to apply them...The KID is the same set up as the modern and the Pirc...The modren changes to the pirc and vice versa!!!

TACTICS! TACTICS! TACTICS! Learn to transpose!! Above all know and practice tactics!!!!

Uh... are you a kid? If not, then I'm actually kind of insulted. You're post has no regard for what is said in mine and is filled to the brim with misinformation about the Pirc, Modern, and King's Indian. I'm also still flabbergasted as to why you felt the need to preach to me about tactics. I fixed the typo though-thanks for that. I didn't realize mixing 2. d4 Bg7 with 2. Bg7 d4 made my post unreadable >.>

/endrant

But seriously, does anyone have some advice for this approach by white? It would be much appreciated.

Maybee you should wait with c5? Develop the kingside first, if you must play c5 what about:

The position after Rxa7 is good for Black (Houdini 1.5 rates Black nearly half a pawn better).

Black has sweet development (powerful Bishop, open a-file, c6 looks good for the Knight), a ready made target (the pawn on e5), few weaknesses and castling in one turn. Black for choice.

Hi skogli, thanks for the reply. I play c5 since the white set-up involving e4, d4, Be3, and Qd2 (which 3.Be3 tries to set-up) is a tough nut to crack from the black side of the modern. c5 attempts to soften up the d-pawn for eventual counter-play. Also, I'm actually quite comfortable after 5. cxd4 d5 but after 5. Bxd4 (which leaves the pawn on c3) I'm actually a bit perplexed as how to meet it.

I am interested in 4... Nf6 in that is seem like a decent alternative, but 5. Bxd4 can't possibly be a good move!? why am I changing my moves to avoid it?

Oh great! I guess that settles it then. I suppose it is kind of obvious that white will have trouble holding the e5 pawn in the variation I gave. Thank you PrawnEatPrawn

Your way of playing it is fine.

White's problem is passive play with 3 Be3, he's not fighting hard enough for advantage and only marginally improves the piece's position.  But 4 Bxd4 is logical enough; when Black has weakened the Kingside dark squares with ...g6 White should try to trade those Bishops, so he might later exploit the weak squares.

Your play is quite good after that, but his attempt to grab a pawn with Bxa7 is awful and PrawnEatsPrawn is correct that Black has more than enough compensation for his pawn with the Bishop pair and an easy development.

White should develop with gain of time by playing Qb3 instead.  This is slightly better than Bc4, when he will have to give the tempo back immediately after ...Nb6.  In either case, though, it is no better than an even game for White, so Black can be well satisfied with equalizing so quickly.