It's time to expand on 1.a3 and the theme of reversed openings. Unless Black has prepared the frequently recommended 1...g6, it’s quite likely your opponent will have a short think after 1.a3. Most likely he will be considering how his various options will fit into his normal opening repertoire (reversed or not).
In some ways 1...e5 is the obvious attempt to swiftly punish White for his non-developing first move. After all it’s possible that White is a pure beginner who has no ideas about development or the centre. 2.b4 can hardly worry Black as it should not be considered a reversed St. George opening (1.e4 a6 2.d4 b5) but rather a toothless Sokolsky line (1.b4 e5 2.a3?!). Nevertheless there are a couple of reasons for Black to reject 1...e5:
1) If Black doesn’t usually open his white games with 1.e4, it may seem illogical to play that move with Black, when White even has a small extra move. We will see one of these reversed lines today. Another is the Mengarini opening 1.a3 e5 2.e4 (or 1.e4 e5 2.a3) to which I will return later.
2) Even if Black normally opens 1.e4 and believes he may steer the game into lines where White’s extra move is irrelevant or even damaging, he may be worried because he doesn’t usually meet 1.c4 with 1...e5 and now fears that he could be lured onto unknown territory with 2.c4 (even though few English players plays 2.a3 after 1.c4 e5, it is not at all uncommon for White to play a somewhat delayed a3).
Z.Plenkovic (2240) - M.Zufic (2370)
Goodbye Summer open Omis 2004
1.a3 e5 2.d4!?
This seems to be a speciality of Plenkovic, who in MegaBase 2006 scores an impressive 4/4 with it. It is one of several reversed approaches that makes sense as it may lead to quite sharp play if White (normally Black) so desires.
2...exd4 3.Qxd4 Nc6
One of Plenkovic wins went 3...Qf6 4.Qd3 b6?? 5.Qe4+ 1–0 Plenkovic-Bazant, Rabac 2004!
Also 4.Qa4 may lead to sharp Scandinavian positions where the extra a-pawn move is a very useful bonus. Compare with the line 1.e4 d5 2.exd5 Qxd5 3.Nc3 Qa5 4.d4 Nf6 5.Nf3 Nc6?! which in practice has been scoring nicely for Black. But after 6.Bd2! Bg4?! 7.d5! Black's position is so difficult that he has started playing 6...a6 in order to continue developing quickly with ...Nc6, ...Bg4, ...Nf6 and ...0-0-0. With ...a6 already in place, the line could be quite attractive.
4...Nf6 5.Nf3 Be7
Here Black has also tried:
a) 5...h6 6.b4 a6 7.Bb2 d6 8.g3 Be7 9.Bg2 Be6 10.Nbd2 0–0 11.0–0 Qd7 12.Rfe1 Bf5 (12...Bh3 13.Bh1) 13.e4 += Plenkovic-Brkic, Split 2005
b) 5...d5 6.Nbd2 6...Be6 7.b4 Nd7 8.Bb2 f6 9.g3 Bd6 10.Bg2 Qe7 11.0–0 Nde5 12.Qb3 Qd7 13.Rad1 Ne7 14.Nxe5 fxe5 15.c4 += Plenkovic-Zvan, Pula 2005.
As can be seen from these examples, Plenkovic likes to play in positional style, with a kingside fianchetto in connection with a pawn expansion on the queenside, but also more primitive play with.Nc3 Bg5 and 8.0–0–0 should be possible.
6.g3 0–0 7.Bg2 d6 8.0–0 Bg4 9.Nbd2 Qd7 10.Re1 Rfe8 11.b4
White again has gone for his favourite set-up. Probably the position is roughly equal, but it is slightly imbalanced and probably feels more familiar to White than Black.
11...Bf5 12.e4 Bg6 13.Bb2 a6 14.Nh4 Ne5 15.Qb3 Qc6 16.Bd4 Qd7 17.Nxg6 Nxg6 18.Rad1
Probably White now has an edge thanks to his bishop-pair.
18...Rad8 19.Nc4 Qc8 20.Ne3 c5 21.Bc3 b5 22.Nf5 Qe6 23.Qb2 Ne5 24.f4 Nc4 25.Qa1 Bf8 26.Bh3!
This should be winning. If Black does nothing, White will play Kg2 and pick up material by a discovered attack on Black's king. But the tactical lines are complicated and White soon spoils his position.
26...Nxe4 27.Bxg7!? Qxf5!
A very good way to mix up things!
Probably the right course would have been 28.Bxf8 Qf6 29.Qxf6 Nxf6 30.Be7 with a decisive advantage to White.
28...Bxg7 29.c3 Nxc3 30.Qc1 Ne2+?
After this check White again gains the upper hand. 30...Nxd1 31.Qxd1 Bd4+ 32.Kh1 Nxa3 33.Bxh7+ Kxh7 34.Qd3+ Kg7 35.Rxe8 Rxe8 36.Qxa3 Re1+ would have given Black a relatively clear advantage.
31.Rxe2 Rxe2 32.bxc5 Bb2 33.Qb1
The position still is very complicated, but I trust Fritz when he claims that White should come out on top.
33...Bxa3 34.c6 Bc5+ 35.Kh1 Bb6 36.Bd3 Rb2 37.Qc1 Be3
This is hopeless but also 37...Rb4 38.Qc3 Ne3 39.Re1 Nd5 40.Bxh7+ Kxh7 41.Qd3+ Kg7 42.Qxd5 is winning for White.
It's possible that Black lost on time, but his position is lost. He must save his rook, but then the a-pawn falls and the white c-pawn decides.