Problem diagram.
White plays.

Source:
Qi Jing Zhong Miao #258 , an ancient collection of mostly kyu level life and death problems.

Analysis:
   Myron Souris

Solution follows    (or click here to download SGF)

Bad timing.
How could such an obvious sente move as White 1 be such a bad move?! Because Black gives up the 5 stones with 2. Through 10, Black lives in the corner!

Black variation.
Note that Black 6 would be a huge mistake that returns the favor back to White. Through 11, Black cannot avoid a bent 4 in the corner.

Correct.
White 1 takes the vital point. Now White has time to push with 3. Through 8, Black has to accept the ko, which White takes 1st.

Black variation.
If Black tries to expand his eye space with 8, White kills Black through 13.

See the SGF for other Black defenses that fail.

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