Pinning the Knight, so as to take off one of the defences of the Kt at Q 4.
... 10. K to Q 2
11. P takes P 11. K to K sq.
12. Castles Q R 12. B to K 3
13. Kt takes Kt 13. B takes Kt
14. R takes B 14. P takes R
15. B to Kt 5: ch. 15. Kt to B 3
16. B takes Q 16. R takes B
17. P to K 6, and wins.