(;AW[pr][pq][qp][qo][pn][nn][mo][mp][nq][nr][ns][os]AB[or][oq][op][np][pp][mr][mq][lq][lp]C[Black plays.

Source:
    "Top Tesuji" poll from the "Weekly" go newspaper.]SZ[19]

(;B[qq]C[The only move!];W[qr];B[ps]C[Again, the move order is important.];W[qs];B[ms];W[ps];B[rq]C[Black captures the corner stones.])
(;B[ps]C[Bad timing.];W[qs]LB[qq:a]C[Now Black's cut at A doesn't work.])
(;B[ms]C[Also bad timing.];W[ps];B[qq]C[The cut looks scary, but ...];W[qr];B[rq];W[rr]C[White's corner stones are safe.]))