(;GM[1]FF[4]AP[Drago:4.22.03]SZ[19]CA[UTF-8]AB[sr][rr][rq][so][ro][qo][po][oo][np][nq][nr][ns][os]AW[sq][sp][rp][qp][pp][oq][or][pr][qr]C[Black to play and kill]
(;B[qq]C[This looks good as White can easily lose a semeai.]
(;W[qs];B[op];W[pq];B[ps])
(;W[rs];B[qs];W[ps];B[op];W[pq])
(;W[pq]C[However White can play here and win the race.]
(;B[qs];W[rs];B[ss];W[rs];B[rr];W[ps])
(;B[ps];W[rs];B[qs];W[ss];B[rr];W[rq];B[sr]
;W[rs]C[White plays "under the stones" to make a second eye with the snap-back shape.])))
(;B[ps]C[This is the correct attack.];W[qq];B[qs];W[rs];B[ss];W[rs]
;B[rr]C[Black plays "under the stones".];W[sr]C[White now has to win the ko to live.];B[ss]))
