3-3 Point Invasion/Original

Sub-page of 33PointInvasion

The information on this page is meant to be introductory in nature. Stronger kyu and dan players are advised to look at 4-4 point 3-3 invasion joseki instead.

Table of contents Table of diagrams
The 3-3 point invasion
The Standard Joseki
The joseki continues
The 3-3 point invasion
Prevention
Preventing the invasion
Overplay (1)
Overplay (2)
Changing the order
don't let white settle in the corner
White shouldn't worry
A more serious attack
A more serious attack
Attacking
Alternate W3
Answer
Queries
Black shouldn't worry

Basic Concepts of 3-3 invasion

Introduction

[Diagram]
The 3-3 point invasion  

Many weak players fear the invasion of W1 in this diagram. Playing Black, they have the idea that their corner territory is taken away, and are, in a sense, correct. After W1, it is White rather than Black who will make territory in this corner.

The 2-2 point invasion at c is typically incorrect, and can be considered a trick play. The idea behind this move is that Black would end up with a heavy group by trying to kill the invasion.



Nevertheless, Black should welcome this invasion. Black shouldn't see this move as an attack on Black's territory; the 4-4 point is not meant to take the corner, but to make thickness and seek a balance between territory and influence. The white invasion at W1 is separated from the rest of the board by the black stone on the 4-4 point. By playing correctly Black will get a strong position. Because of this, stronger players play W1 only if the position on the edges is such that a white stone at a or b will come under attack.

White, for his part, should resist the temptation of invading here too soon. The general principle is that White should seek to invade at W1 the move before black would protect the area.


3-3 Invasion Joseki

[Diagram]
The Standard Joseki  

To W1 Black will invariably answer with B2 (or Black at W3, on the other side). To choose which way to block, the general rule here is to block on the wider side, seeking to maximise the usefulness of the outside strength black is building.
W3 ensures that White's corner will not be too small.

B4 is an important move, preventing white from making progress out into the centre.

White plays at W5 to avoid Black playing at the same point.

B6 is the most usual continuation, although the severe double hane of B6 at 7 is played in some circumstances.

Usually crawling along the 2nd line is bad, but W7 is important to prevent Black turning here in sente. White should resist the temptation to continue crawling at a. Every extra point white takes, is far less valuable than the outside strength that Black takes.


What if B8 plays at "a"?

erikpan: Just a quick question: Is there anything wrong with W3 at b instead?[4]

[Diagram]
The joseki continues  

Next, White plays hane at W1, and the joseki ends with B4.

White has sente and a few points in the corner, but Black's wall is like a block of concrete, controlling a large part of the board.

This result is regarded as good for Black locally, but is often White's best choice, nonetheless. Later in the game the cut at a might be a problem for Black, see Squeeze for more discussion how and when to defend. See Hovercraft for Black attacks on the corner and the proper defenses.

Can White change the order of play here?


Getting sente?

[Diagram]
The 3-3 point invasion  

With the knights jump black can get sente, if the upper side isn't very important.


3-3 Invasion Prevention

[Diagram]
Prevention  

The usual way to prevent the 3-3 point invasion is a stretch at B1 or a depending on where friendly stones are nearby. The one-space jump at b and the diagonal at c can also be used, though they are seen less frequently.


[Diagram]
Preventing the invasion  

This shape is also seen in situations like this, where White has played an approach move, with the same intention of preventing the 3-3 invasion


Other Advanced Variations

The diagrams above cover the most basic moves, but unsurprisingly, (this is Go, after all) there are more complexities and subtleties that one can investigate:

[1] Over-Hane

If black seeks to get more by playing at B1 in the diagram below, then he risks disaster...

[Diagram]
Overplay (1)  

B1 here instead of B8 in the joseki (W2 in this diagram) is overdoing things. After W8, Black has problems.

[Diagram]
Overplay (2)  

White could also attack the black stones at the left with these moves. Either way, White has destroyed Black's thickness, and has good chances of getting even more.



Charles I've seen a pro as White play directly at B5 after B1 here.

^tderz: cf. with RTGProblem31


[2]

W plays the reverse order

[Diagram]
Changing the order  

Here White swaps the order of play, turning at W1 before playing the hane at W5.

The danger is that Black may be able to answer W3 with B4 rather than the usual B8. This lets Black shut White into the corner with B6 (particularly as 'a' is Black's sente). White ends up with a smaller corner than in the joseki, and Black may be in a position to make territory on the left. The disadavantage for Black is the aji of the cut at 'b'.


[3]

B tries to kill the invasion

If black is already very strong on the outside, then letting white live small in the corner, overconcentrating the new black wall is a bummer. Instead, black can try to kill the 3-3 invasion by undermining the eyespace in the corner and forcing white to run out into the center where sufficient black resources can deny white outside eyespace and a route to safety. How to undermine the eyespace in the corner?

[Diagram]
don't let white settle in the corner  

Follow-ups and/or expansions welcome here.

One idea from 10x10CornerGame1 is to let white get the L group in the corner, but not a second eye or connection on the outside.

[Diagram]
White shouldn't worry  

Charles Matthews W1 is more than adequate: it makes black+circle into quite a bad play [5]. White shouldn't fear this.

[Diagram]
A more serious attack  

In fact B2 directly, in reply to W1 is a more refined version of this technique. There are a few contexts in which it is strong.

[Diagram]
A more serious attack  

Now what?

Charles There is no need to play W3: just play W5 (1-2-3 principle).

[Diagram]
Attacking  

Black can make it unobvious how White lives up to B7.


[4]

[Diagram]
Alternate W3  

erikpan: Just a quick question: Is there anything wrong with W3? I've had some success with it, admittedly at the 16k-ish level. When black is already not too strong outside it usually seems possible to live small and steal some territory - unless someone can provide some alternative variations for black?

[Diagram]
Answer  

The turn, B4, is a good play for Black. Not only does it block White in this direction, it threatens a.


There is more detail at 4-4 point 3-3 invasion joseki and the following pages:

Queries

[Diagram]
Queries  


mat Very often I ask myself if a 3-3 point invasion still works in the presence of more than one black stone. I've set up a page to discuss which of those work and which don't: 3-3 Point - When Does It Work


Original authors: Andre Engels, Adamzero, JamesA Contributors: Tinia? MarkusKovisto? Reuven Paul Clarke


[5]

[Diagram]
Black shouldn't worry  

BruceWayne You are right normally, but as the description says, if B has a very strong wall such as the marked stones then W will die.


3-3 Point Invasion/Original last edited by tapir on September 25, 2009 - 21:49
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