Korubko wrote in the forum: "The turning point [of the championship] came in the interesting game against Klaus. After [22.m18] I actually believed for a while that the game is over for me. To my great surprise, at-first-glance pointless move [23.e18] showed to be the key to win."

I don't get it, though. It looks like 23.m16 should work fine, and I don't see how the digression on the left makes a difference.

Ok, this might be a hasty comment, but I was looking at this at the time of the game, and it seemed to me that the danger was |23.m16 24.o14 25.i16 26.o19 27.s18 28.q18 ... can you poke holes in that? The contribution of |23.e18 was that it made the |27.e14 link possible, which makes the tenuous h11-g15-k17 connection work, which means he can skip the i16 step in the above line, which puts him one move ahead and winning. I could be wrong...

Thanks, Alan. That was indeed the threat I missed.

But I still don't get the value of the e14 peg (which I agree must be the key). Using the o14 move after the digression, I guess the line is |30.o14 31.o15 32.i16. Then what? I guess the good options are 33.j13 or 33.j15, but they don't seem to work.

|30.o14 31.o15 32.i16 and then 33.k13. Now, why didn't that work earlier? Because |23.m16 24.o14 25.k13 26.o19 27.s18 28.q18 or |23.m16 24.o14 25.o20 26.i15 27.e14 28.g16 29.e18 30.f18. So, I guess what that last line shows is that the value of the e14 peg is that it kills Black's i15 threat (i16 is a red herring because of k13).

And thanks again. Now it seems so clear that I can't imagine how I missed it (not the o14-o19 combination, which still seems hard to me, but the i15 threat and the relevance of the e14 peg).