(Referenced by 191; 192; 732; 897)

Guzumi @ :
This is the earliest moment that it might be sensible for Black to play guzumi after the completion of the hanezeki.

!!! In this section White basically gives atari on the hanezeki's tail after Black's guzumi. All other moves will lead to a change in the order of moves for a later played guzumi. !!!

We are not convinced that our endgame is optimal. However, we tried to apply it equally to the different variations. In our opinion, White wins clearly here, perhaps by about ten points.

We marked the approximately 20 points of white territory (/), which will disappear during the journey of the hanezeki's tail across the board.

Please understand the order of moves shown here - with the guzumi first, then the push, then the hasami-tsuke late - in the historical context.

/// Guzumi @ :
With the hanezeki's tail (), Black has run through White's potential territory on the lower edge, and in the centre. By contrast, with her moves White has occupied mostly neutral points ().

We think that Black now wins by a very small margin.

/// Guzumi @ :
With , Black has continued to destroy potential white territory at the top; White has still occupied largely neutral points with . All the potential territory, White has hoped for to get in the centre, has gone now. If we assume the same peaceful sequence as in the previous diagrams, it now will be Black, who wins significantly, perhaps by up to approximately fifteen points.

So, White will not really play at here, but must respond to the guzumi, with a move at . Black then continues with the "usual" Crosscut Sequence, starting with a move at 66; this will result in a change in the order of moves with our solution (that Black wins by only three points).

However, Black's further destruction of White's territory with is more than over-compensated for by the fact that the fight gets closer, and closer, to the upper left corner, and so the potential of White's threats there increases, due to the presence of her -stones. So, White has the chance to attack Black's upper left corner, with (this move forces Black to live in the upper right), and . As shown earlier ( 434), this variation ends with five points for Black, according to our estimation.

- :
Another major turning point is the Crosscut Sequence in the upper left centre. The efficiency of White's moves - with respect to the endgame - is noticeably higher than those of Black's. Under "normal" circumstances - with no major groups fighting each other - Black would rather play at 66. rescues one stone only, while threatens the lower left corner. And, with , Black saves only his single stone to the right, while White, with , captures Black's group on the left, not to mention her later gains when Black sacrifices repeatedly in the nakade.

/// Guzumi @ :

Here Black still has the choice between the rescue of his -group at the left edge, and the prevention of a massive loss of territory and stones () in the upper left corner. The top left corner is bigger than the left side, so Black has to discard his nakade stones, if he ever wanted to win the game. Our trials with the endgame always ended with a very close result, but we feel that it is more likely that Black will win, probably by about two points ( 219).

If Black insisted on saving his nakade stones, he would not be able to withstand White's forceful moves in the upper left corner successfully. Black would lose the game unnecessarily by about five points ( 389).

/// Guzumi @ :

Once the Crosscut Sequence has been completed, Black no longer has any option; he loses his -group at the left edge outright. Here we tend to feel that White will get a sure win, by at least two points ( 224).

- :
If Black, and White, follows the course of the professional solution any further, White lets slip two opportunities to occupy the guzumi point on the right edge. The first one with , unforced capturing Black's nine nakade-stones; ...

... the second one with , unforced giving atari inside the nakade.

/// Guzumi @ :

So, due to White's sub-optimal play before, Black gets another chance to play guzumi. Detailed explanations on this development, which will end in Black's defeat, can be found in the sections "Variations of the Professional Solution" ( 731), and "White's Unforced Atari in the Nakade" ( 822). After , Black has the choice between , and , neither of which will end successful for him.

Conclusion:
Immediately after the completion of the hanezeki, Black cannot play the guzumi, because he has not destroyed enough of White's potential territory yet.

Around move 48, the tables will turn. Black still destroys White's territory, while White occupies mostly neutral points. Probably White will answer the guzumi locally, because this leads to a change in the order of moves with our solution, and so to a better final result for her.

If the hanezeki's tail comes very close to the upper left corner, White gains more by the resulting potential threats than she loses in territory.

With the Crosscut Sequence, Black loses many of his earlier options, because this fixes the shape. White is now almost always expected to win, because her previous moves are found to be of more value for the endgame than Black's.

The conclusion remains that the most favourable moment for playing the guzumi is indeed with move 65, immediately before the start of the Crosscut Sequence.