There is a remarkable opening move which looks like a White blunder in the Gruenfeld.
And it goes like this:
1.d4 Nf6 2.c4 g6 3.Nc3 d5 4.cxd5 Nxd5 5.Na4!?
Here’s a diagram.
Bringing up the question, “What benefit(s) does White attain with his knight sitting idly and alone on a4?”
Well, for one, after White gets around with .e4, the Black’s knight has to move. His usual move of …Nxc3 is out of the question as White has no piece or pawn on c3. So where does Black’s knight then move? If …Nf6, then he invites .e5. And …Nb4 puts his knight out of play and is subject to .c3. So …Nb6 is practically forced, where it is partly out of play and but no pawn is threatening it.
The second benefit White has is that with the knight out of the way, his queenside is open for his other pieces, not to mention he can now play .c4 at some point. In fact, most of the action that originates from this bizarre knight move is of a queenside nature.
The earliest master game with this move can be found in the following game.
Ashot Nadanian (2325)-Varuzhan Akobian (2270)
1.d4 Nf6 2.c4 g6 3.Nc3 d5 4.cxd5 Nxd5 5.Na4 e5 6.dxe5 Bb4+ 7.Bd2 Ne3 8.fxe3 Bxd2+ 9.Qxd2 Qh4+ 10.g3 Qxa4 11.Qd4 Qa5+ 12.b4 Qb6 13.Bg2 O-O 14.Rc1 Be6 15.a4 c6 16.Nf3 Rd8 17.Qf4 Na6 18.Rb1 c5 19.b5 Nb4 20.Qh6 Nc2+ 21.Kf2 c4 22.Rbc1 Bf5 23.Rxc2 Bxc2 24.Ng5 Qc7 25.Qxh7+ Kf8 26.Ne6+ 1-0
Here’s some later games showing White’s attacking possibilities.
Alexander Naumann (2385)-Alexander Lytchak (2390)
German U20 Ch.
1.d4 Nf6 2.c4 g6 3.Nc3 d5 4.cxd5 Nxd5 5.Na4 Bg7 6.e4 Nb6 7.Be3 O-O 8.Rc1 f5 9.exf5 Bxf5 10.Nc5 Qd5 11.a4 Nc6 12.Ne2 Nc4 13.Nf4 Nxe3 14.fxe3 Qd6 15.Bc4+ Kh8 16.O-O e5 17.Nfe6 Bh6 18.Rc3 Bxe6 19.Nxe6 Rxf1+ 20.Qxf1 Qe7 21.Ba2 Rc8 22.d5 Nd8 23.d6 1-0
Stepan Lobanov-Leonid Sharikov
Novokuznetsk Open, 1998
1.d4 Nf6 2.c4 g6 3.Nc3 d5 4.cxd5 Nxd5 5.Na4 Bg7 6.e4 Nb6 7.Be3 O-O 8.Nf3 Nxa4 9.Qxa4 c5 10.Rd1 cxd4 11.Nxd4 Qe8 12.Qa3 a6 13.Nb5 Be5 14.Bh6 Bd7 15.Bxf8 Nc6 16.Nc7 Bxc7 17.Bh6 Bd6 18.Qd3 Nb4 19.Qc3 f6 20.Bc4+ +/- Kh8
21.Rxd6! Nc2+ 22.Kd2! b5 23.Rxf6 1-0
Szabolcs Laza, (2173)-Anita Gara (2385)
Hungary Team Ch., Dec. 17 2017
1.d4 Nf6 2.c4 g6 3.Nc3 d5 4.cxd5 Nxd5 5.Na4 Bg7 6.e4 Nb6 7.Be3 O-O 8.Nf3 Bg4 9.Nc5 Nc6 10.Nxb7 Qb8 11.Ba6 e5 12.d5 Nb4 13.Nc5 N6xd5 14.Bb7 Nxe3 15.fxe3 Bxf3 16.gxf3 Rd8 17.Qb3 Bf8 18.Bxa8 Bxc5 19.Bd5 Nxd5 20.exd5 Qxb3 21.axb3 Bxe3 22.Ke2 Bd4 23.Rhd1 Rxd5 24.Rxa7 Rb5 25.Ra8+ Kg7 26.Rd3 c5?! (Black’s bishop is on an overwhelming square overlooking everything in front of it, and because it is supported by two black pawns means it is not forced off going to be driven off its awesome square. Unfortunately, it also means the Bishop can’t move backwards, which make a difference in this endgame.)
27.Ra6 h5 28.h3 Rb7 29.Rc6 Kh6 30.h4 Kg7 31.Rc8 f6 32.Rc6 g5 33.hxg5 fxg5 34.Re6 h4 35.Kf1 Ra7 36.b4 cxb4 37.Rb3 h3 38.Rxb4 g4 39.fxg4 Ra1+ 40.Ke2 h2 41.Rb7+ Kf8 42.Rf6+ Ke8 43.Re6+ Kd8 44.Rg6 Re1+ 45.Kd2 Rd1+ 46.Kc2 Rc1+ 47.Kb3 Rc7 48.Rg8+ Kd7 49.Rxc7+ Kxc7 50.Rh8 Bg1 51.g5 e4 52.g6 e3 53.Kc2 e2 54.Kd2 Bd4 55.Rxh2 Bxb2 56.g7 1-0
However, the move 5.Na4 remained under the radar for years. Until it was played by a three-time challenger of the World Championship who played it a European Zonal Tournament.
GM Korchnoi (2625)-GM Emil Sutovsky (2575)
Dresden, Germany, 1998
1.d4 Nf6 2.c4 g6 3.Nc3 d5 4.cxd5 Nxd5 5.Na4!? Bg7 6.e4 Nb6 7.Be3 O-O 8.Nf3 Nxa4 9.Qxa4 c5 10.Rd1 Qb6 11.Rd2! (This TN is such a good move that it became part of theory.) 12…Bd7 12.Qa3 cxd4 13.Nxd4 Qc7 14.Be2 e5?! 15.Rc2 Qd8 16.Nb5 Nc6(16…Bc6 17.O-O Bxe4 18.Rd2!) 17.Nd6 Qb8 18.Bc4 Nd4 19.Bxd4 exd4 20.O-O Be6 (20…Be5? 21.Nxf7! and White’s attack comes first and fast.) 21.Bxe6 fxe6 22.Rfc1 Be5 23.Rc7 Bxd6 24.Qxd6 Rf7 25.Qxe6 1-0
And now everyone seemed to take notice.
GM T. Gareev (2614)-Ge. Antal (2519)
Irvine, CA, Aug. 2 2010
1.d4 Nf6 2.c4 g6 3.Nc3 d5 4.cxd5 Nxd5 5.Na4 Bg7 6.e4 Nb6 7.Be3 O-O 8.Nf3 Nxa4 9.Qxa4 c5 10.Rd1 Qb6 11.Rd2 Bd7 12.Qa3 cxd4 13.Nxd4 Qc7 14.Be2 Bc6 15.f3 Be5 16.g3 Bd6 17.Qc3 Rc8 18.Kf2 Na6 19.Nxc6 Qxc6 20.Qxc6 Rxc6 21.Bb5 Rc7 22.a3 Bc5 23.b4 Bxe3+ 24.Kxe3 Rac8 25.Rhd1 Nb8 26.Rd8+ Kg7 27.f4 f6 28.e5 fxe5 29.fxe5 a6 30.Ba4 a5 31.bxa5 Rc3+ 32.Kd2 Rxd8+ 33.Kxc3 Rc8+ 34.Kb4 Na6+ 35.Kb5 Rc6 36.Bb3 Nc7+ 37.Ka4 Rc5 38.Rd7 Kf8 39.Rd8+ Kg7 40.Rc8 g5 41.Bd5 Rxd5 42.Rxc7 Rxe5 43.Rxb7 Re4+ 44.Rb4 Re6 45.Kb5 Re3 46.a4 1-0
GM Hao Wang (2736)-GM F. Caruana (2779)
Paris, Sept. 23 2013
1.d4 Nf6 2.c4 g6 3.Nc3 d5 4.Nf3 Bg7 5.cxd5 Nxd5 6.Na4 O-O 7.e4 Nb6 8.Be3 Nxa4 9.Qxa4 c5 10.Rd1 Qb6 11.Rd2 Bd7 12.Qa3 cxd4 13.Nxd4 Qc7 14.Be2 Bc6 15.O-O Bxe4 16.Nb5 Qc6 17.f3 Bd5 18.Qxe7 Re8 19.Qg5 Na6 20.Qxd5 Qxd5 21.Rxd5 Rxe3 22.Bc4 Re7 23.Rd2 Bh6 24.f4 Nc5 25.g3 a5 26.Rd5 Ne4 27.Rfd1 Bf8 28.Rd8 Rxd8 29.Rxd8 Kg7 30.Kg2 Nf6 31.Kf3 Rd7 32.Rxd7 Nxd7 33.Nc7 Bc5 34.Bb5 Nf6 35.Ne8+ Nxe8 36.Bxe8 Kf8 37.Bb5 Kg7 38.Be8 Kf8 39.Bb5 Kg7 40.Ke4 1/2-1/2
Saric (2425)-Bo Vujacic (2269)
Serbian Team Ch.
Palic, Sept. 4 2014
1.d4 Nf6 2.c4 g6 3.Nc3 d5 4.cxd5 Nxd5 5.Na4 Bg7 6.e4 Nb6 7.Be3 O-O 8.Nf3 Nxa4 9.Qxa4 c5 10.Rd1 Qb6 11.Rd2 Bd7 12.Qa3 cxd4 13.Nxd4 Qc7 14.Be2 Bc6 15.O-O e5 16.Nb5 Bxb5 17.Bxb5 Nc6 18.Rc1 Rfd8 19.Rdc2 Bf8 20.Qa4 Qd6 21.Bc5 Qf6 22.Bxc6 Bxc5 23.Rxc5 Rd2 24.Rf1 bxc6 25.Rxc6 Qg5 26.Rc2 Rd4 27.Qa5 Qf4 28.Re2 Rxe4 29.Rxe4 Qxe4 30.Re1 Qc4 31.b3 Qc2 32.Rxe5 Rc8 33.h3 Qb2 34.g3 h5 35.Re1 h4 36.g4 Qd4 37.Qe5 Qd2 38.Qe2 Qc3 39.Qe3 Qa5 40.Re2 Rc3 41.Qe8+ Kg7 42.Qe5+ Qxe5 43.Rxe5 Rxh3 44.Ra5 Rf3 45.Kg2 Rf4 46.g5 a6 47.Rxa6 Rg4+ 48.Kh3 Rxg5 49.Kxh4 Rg2 50.f3 f5 51.Kh3 Rg1 52.Kh2 Rb1 53.Kg3 g5 54.Kf2 f4 55.Ke2 Kf7 56.Rd6 Ke7 57.Rd1 Rb2+ 58.Rd2 Rb1 59.Rd1 Rb2+ 60.Rd2 Rb1 61.Kd3 Ke6 62.Ke4 Re1+ 63.Kd4 Rf1 64.Rd3 Kf5 65.a4 Ra1 66.Kc5 g4 67.fxg4+ Kxg4 68.Rd8 f3 69.Rf8 Kg3 70.Rg8+ Kh3 71.Kb5 f2 72.Rf8 Kg2 73.a5 f1=Q+ 74.Rxf1 Kxf1 75.a6 Ke2 76.b4 Kd3 77.Kb6 Kc4 78.b5 Ra2 1/2-1/2
It may be that Black can force a draw. But he has to work for it. Maybe you can find some improvements for White.