Mr. Ortner asks:

I usually don’t care to update the openings I play. That’s why my reference book for the Benko gambit is from 1991 (by Suetin).

Recently, I came across a review of Neil McDonald’s new book THE BENKO GAMBIT REVEALED, where I read the following:

“...he explains why you have to play g6 before taking on a6 with the 
            bishop.”

I don’t know McDonald’s book and wondered what’s wrong with taking on a6 with the bishop immediately. Moreover, my book doesn’t see anything wrong with the line 1.d4 Nf6 2.c4 c5 3.d5 b5 4.cxb5 a6 5.bxa6 Bxa6 either.

Is there really something like a refutation of this line? Should I think about buying a new opening book for the Benko?

Silman replies:

A lot of things change in theory in a very short time, but the need to get new books and keep up with those changes depends on the level of competition you face. If you’re a serious tournament competitor, you really should upgrade. If you just play for fun on-line or with friends, then there’s no reason to do so.

The view that an immediate 5…Bxa6 is inaccurate has been generally accepted for a couple decades. However, this is based on the assessment of the following line: 1.d4 Nf6 2.c4 c5 3.d5 b5 4.cxb5 a6 5.bxa6 Bxa6 6.g3 d6 7.Bg2 g6 8.b3! Bg7 9.Bb2 0-0 10.Nh3 Nbd7 11.0-0 and though Black has tried just about every possible move and idea, White seems to come out on top.

Because of this, 5…g6 became Black’s main choice. Now Black can meet 6.b3 Bg7 7.Bb2 0-0 8.g3 with 8…Nxa6 9.Bg2 Bb7 when Black is doing well due to the possibilities of …Nb4 and/or …e6.

In a nutshell, you lose nothing by choosing 5…g6, since you can always hack off the pawn later by …Bxa6. Since there’s no downside, why not use this move, which keeps your options open and guards against the double fianachetto line mentioned above?