(;GM[1]FF[4]CA[UTF-8]AP[CGoban:3]ST[2]
RU[Japanese]SZ[19]KM[6.50]
PW[Juyong koh]PB[Gansheng Shi]
;B[pc]
;W[dp]
;B[pq]
;W[dd]
;B[fq]
;W[cn]
;B[dr]
;W[cq]
;B[iq]
;W[po]
;B[pm]
;W[no]
;B[nq]
;W[qq]
;B[qr]
;W[qp]
;B[rr]
;W[qm]
;B[ql]
;W[pl]
;B[qn]
;W[rm]
;B[rn]
;W[pn]
;B[om]
;W[rl]
;B[qk]
;W[rk]
;B[so]
;W[qj]
;B[mn]C[Note this move requires a ladder.  See the variation for why.]
(;W[mq]
;B[mo]
;W[np]
;B[nr]
;W[mp]
;B[ko]C[To here the white groups seems to be very difficult.  However Mr. Koh has a brilliant sequence prepared to rescue it.]
;W[jp]
;B[kp]
;W[jq]
;B[kq]
;W[kr]
;B[lr]C[Watching this it looked like Mr. koh was preparing to sacrifice, and the capture would give black the advantage.  However the next couple move revealed Mr. Koh's plan. ]
;W[nn]
;B[nm]
;W[mm]TR[mn][mo]C[Now I saw that if black can get A in sente black's two stones can be captured.  Black at this point thought long looking for a sequence that does not allow A in sente, but could not find one and had to concede the capture of the triangle stones.  See the variation for the ladder capturing sequence.]
(;B[pk]
;W[ml]
;B[pj]
;W[qi]
;B[pi]
;W[nk]
;B[ok]
;W[lo]
;B[jr]
;W[kn]
;B[qh]LB[qh:A]C[In the game black does get some gain from getting A, so he can still fight, but the white sequence was very impressive to me.]
;W[rh]
;B[rg]
;W[ri]
;B[qg])
(;B[ok]
;W[ml]
;B[nk]
;W[lo]
;B[ln]
;W[kn]
;B[lm]
;W[km]
;B[ll]
;W[lk]LB[lo:A]C[At some point b must take at A, and then...]
;B[lp]
;W[kl]
;B[lo]
;W[jo]
;B[lq]
;W[mr]C[Complete collapse!]))
(;W[nm]
;B[nn]
;W[on]
;B[ol]
;W[mm]LB[nk:B][ln:A][iq:C]C[After this sequence if the ladder works for white A capturing the two stones and B capturing the group above are mia (equivelent good options). In this game C breaks the ladder, so black can play this.]))