Gruenfeld Defense, Smyslov Variation

The next game in Smyslov's Sparklers uses an opening that I've never understood, a variation named after Smyslov. I decided to research opinion on it. The diagram show the position after 1.d4 Nf6 2.c4 g6 3.Nc3 d5 4.Nf3 Bg7 5.Qb3 dxc4 6.Qxc4 O-O 7.e4

Of 5.Qb3, Kasparov wrote, 'This thrust was considered to be White's most formidable weapon [against the Gruenfeld] since the time of the 12th game of the 1935 Euwe - Alekhine match.' Fischer anticipated my own thinking when of the same move he wrote, 'The main line, but I don't believe this early development of the Queen can give White anything.' (60 Memorable Games, no.39; Botvinnik - Fischer, Varna Olympiad 1962)

(After 7.e2-e4)

Writing in 1964, Horowitz called the variation 'The Two Pawns Game', and said:

This method is most frequently encountered against the Gruenfeld Defense. White has a strong center but must guard against a breach. Black, on the other hand, has a plus in development and must bring pressure against the enemy d-Pawn. In this connection the thrust ...c5 is of great significance and constitutes the key to the most important lines of the defense. Many systems have been devised against White's set-up.

The Smyslov System: Black plays 7...Bg4, followed by the maneuver 8...Nfd7 and 9...Nb6. This converts Black's King Knight from a defensive piece to an aggressive one and keeps open the d-file and the long diagonal for concentrated action.

The Prins System: 7...Na6; The line is double edged in that it requires impeccable technique on the part of the defender.

The Boleslavsky System: The objectives here are different from the foregoing. Black's prime target is to enforce ...e5 in conjunction with the dispossession of White's Queen Knight from its central post. The latter is accomplished by means of ...c6, ...b5, ...Qa5, and ...b4. The usual thrust ...c5 may still play an important role later.

In discussing his game with Botvinnik, the only time he played the then World Champion, Fischer wrote:

Also interesting is Donald Byrne's provocative 7...Nc6. [As for Smyslov's Variation, 7...Bg4 8.Be3 Nfd7], So far theory has found no way to derive any clear advantage for White.

He gave several variations to make his point. Of the move 7...Bg4, Smyslov wrote:

Black puts into effect a plan involving action against the center by the pieces -- one of the most interesting problems of modern chess strategy.

Kasparov explained 8.Be3 Nfd7 with:

An unexpected and far from obvious reply, which is hard to explain from the position of the old classical school. But the Gruenfeld opening itself was a product of the new chess era, and Smyslov realized that only something extraordinary could help Black carry out the main idea of the opening -- a Pawn attack on the strong enemy center. By opening the diagonal for the g7 Bishop, driving back the White Queen (by ...Nb6), and developing the other Knight at c6, he sets up pressure on the d-file, and in the event of d4-d5 he can undermine the center with ...c6 and ...f5.

But he also warned:

More usual at present is 7...Na6, or Alekhine's 7...a6.

Clearer? Yes, thanks, although I count five different possible plans for Black: 7...Bg4, 7...Na6, 7...c6, 7...Nc6, & 7...a6.