After Pass Move, Roln111 Still Finds Victory

As you may know, roln111 (Ilya Shikshin) and artem92 (Artem Kachanovskyy) have somewhat of a rivalry on KGS. Since December 7, 2008, they have played 17 matches (12-5 in favor of roln with this game). In this game, Ilya seemed to have taken a commanding lead before a serious slip:

After an early White approach, Black tenukis at 15 to take the last empty corner (the local follow up is at N6). White responds by haning and establishing some center influence and pincering with 22. Black 23 looks to be a mistake, the one space jump seems much easier to play, there doesn't seem to be any reason to play the diagonal there. The result to White 34 is White harassing the weak black group and building influence to severely attack Black's corner. In this light, Black 31 seems to be a mistake and better of solidly defending the corner. Through 62, White has successfully enclosed Black's group and built an imposing influence on the top. Black 63 seems to makes the matter worse, inducing White 64.

White next checks the Black moyo on the bottom and Black invades with 70 to split White and attack the weak group. In the ensuing fight, roln misreads with 94, leading to a dead corner, but his outside manages to live. With that, and Black's moyo being mostly reduced, White firmly encloses the top with 128, seemingly saying: I have won. However, victory not so easy to come by.

The issue comes with Black 151, White could have easily connected and lived wholesomely with F9, but chose instead to counterattack at F11. A semeai in the center follows where roln111 makes a huge mistake. At White 166, he plays F15 where it should have been E13 (See Variation). However, White manuvers himself into a much less favorable non-direct ko. Then comes the even more shocking part. White plays D1 (178) as a ko threat! This is a 15 kyu reading mistake!  It is not a threat at all and negative 1 point in gote.

Nevertheless, roln111 still manages to squeak out a 3.5 win in yose, perhaps White's lead was simply too big.