What's Going on With 1. a3!?

Introduction

1 a3 is a strange and innocuous looking opening move and this makes the few occasions where it has been essayed at the highest levels of chess all the more interesting

The most notable instance to my memory is the round 11 game between Awonder Liang and Leinier Dominguez Perez in the 2024 US Championships:

Unsurprisingly, 1. a3 has a tendency to transpose into other openings. In this case after move 4 the game had transposed into a London where white has played a3 for some reason. Not the most inspiring result, it's hard to come up with ideas against players who know everything, but maybe for us mortals there is more to this move than first meets the eye?

The Inner Workings of 1. a3

Passing The Baton

By playing a3 we offer black the opportunity to choose their setup and play with the white pieces, at the same time we eliminate their most ambitious options. The Spanish is no longer an option for obvious reasons and any Queen's Gambit setup risks losing a pawn as black is poised to hold on to their material after dxc5. We attempt to take full advantage of the paradox of choice and give our opponent as much opportunity as possible to go wrong in a position that they could not have anticipated.

Subverting Expectations

Most players come to the board with some sort of plan for how the game will develop. At the top levels of chess this preparation is turned up to eleven, every one of these players has put in painstaking work to bulletproof their repertoire and always stay in control. Since the game is virtually guaranteed to develop organically after a3 it forces black to abandon any preconceptions they came to the game with and play for themselves.

Fight or Flight

Because this opening is so unexplored, it's unlikely that our opponent will choose the correct level of ambition/aggression when combating it. It's not really an opening that can be "punished" and any improvised efforts to do so are often irrational and risk backfiring. More likely than over aggression is timidity. Most players will default to some comfortable, unambitious setup in this unfamiliar situation which makes their play predictable and exploitable.

A Proposal

Black has four main responses to 1.a3 - d5, e5, Nf6, and c5. Ideally the response to each of these moves should have

1. Transpositional Value - tricking our opponents into theoretical variations that they do not play

OR

2. Inherent Value - we leverage the move a3 to allow us to achieve something we could not with the black pieces and therefore bring the game into unique waters

d5

Breaking it Down:

In general after d4-d5 black is faced with a decision between a London setup and a queen's gambit declined setup. If black chooses a London setup, by playing c4 and Qb3 white can always force black into a concession, especially because the most combative line in the normal London (where Nc3 is played intending Nb5) is no longer possible.

If black attempts to go for a queen's gambit declined setup, an interesting idea for white is "justifying" a3 by meeting Be7 with c5 and the intention to build up a large pawn wedge with b4 as this forces the game into very unusual but still equal waters where familiarity can create a big edge. This can also be achieved through 1.d4 d5 2. a3.

e5

e5 is not in general a great response to a3 because it allows the white to enter the reverse Sicilian (or King's English) where a3 is always a useful move. Even if black is an e4 player, facing the Sicilian a real tempo down requires a level of preparation that they are unlikely to have unless they play the King's English (which they most likely do not)

Nf6

Nf6 is a very principled approach to a3, trying to play a more useful but still flexible move. I present two interesting approaches.

c4:

This is what we go for if we suspect our opponent is committed to the safe King's Indian Setup, we can meet g6 with b4 and arrive at a relatively unique equal position if black continues with their standard plan. In the rare case that black plays c5 white is left with a somewhat uninspiring symmetrical english.

d4:

We have the intention to follow up with Nd2 at which point black must either accept white building a center with e4 and d4 (notably not c4) included or play d5 and leave the standard King's Indian setup

c5

c5 is a very critical response but also quite rare, the logic makes sense, if white is committing to a3 it is less likely that they will be able to castle queenside and effectively punish the Sicilian. If black does not play the English as white it is easy to transpose into a position that they do not understand how to approach just by pretending you have the black pieces and are facing 1. c4.

Random Moves

Seeing 1. a3 it is likely that our opponent may be induced to play something equally strange in response, especially in faster time controls. Some short commentary is provided below.

So is 1. a3 worth playing?

Maybe? Looking at the statistics it is clear that a3 has a serious impact on opening choices relative to if the colors were simply reversed at the start of the game. Black has to wonder: can they play their response to d5 without modification? Should they try to pretend they have the white pieces or just try to play principled chess? There is real value to the confusion and tension that a3 adds to the start of the game and if the objective flaws of the move can be mitigated it becomes more of a reasonable choice. This concept is perfectly in line with the trend in modern theory: as increasingly powerful engines continue to prove that almost anything can work with the right approach, players are now oftentimes prioritizing surprise value over objective merit.