tesuji from amateur games 4

Tesuji  

White to play. Tesuji time.

/Attempts
/Solution?

Dieter: I was definitely proud of my tesuji!

Bill: It is very nice, Dieter. :-)

unkx80: This is an extension of Beginner Exercise 40. It is easy when posed as a problem, but never so obvious in games. Congratulations! ;)