Ko fight example from a pro game - 3

Start of ko  

This is a game between Zhang Li, 3p, and Huang Yizhong, 6p, in 2005 (2005-10-08, 7th Chinese League A, round 13, W+R 7.5 komi, complete game record). White invites a ko with , which is necessary to fight the capturing race in the corner. starts the ko.

at  

is the first threat and it is a local ko threat. is also a local threat. Next - prepares which is necessary to continue the ko. is another local threat.

at , at  

is a local threat and must respond again. seems to finish the ko, but . . .

at  

Black throws in at , a tesuji that reminds of the two-stone corner squeeze. then takes the ko, which has become a two-stage ko. Finally, resolves the ko.

The last local threat, at , is worth a closer look . . .

Ko threat explained

If resolved the ko, connects. cannot resist, as makes miai of a and b. Probably should be played at a immediately.