(;
AB[pr][or][qq][qp][pp][np][mp]
AW[rr][qr][rq][rp][oq][pq][nq]
C[Black plays.

The correct tesuji here may be hard to spot, because Black's shape looks so thinn.

Source:
    "Top Tesuji" poll from pros in the "Go Weekly" newspaper.]
(;
B[mq]
C[A mistake.  In different liberty configurations, this descent might be correct to squeeze White to make good outside thickness.];
W[nr];B[mr];W[os]
LB[ms:A]
C[Black makes some outside thickness, but Black loses the 2 stones.  And later, the sente endgame hane at A is White's privilege.]
)
    (;
    B[nr]
    C[Black's shape looks too thin to extend here, but this extension is the tesuji.];
    W[mq]
    C[White cannot escape with these stones.];
    B[lq];W[mr];B[lr]
    C[Black captures the stones and creates solid outside thickness.]
    )
)

