The more you study ...

I'm a great believer in luck and I find the harder I work, the more I have of it.
- Thomas Jefferson

I played a 19x19 against Masakari (30k) and won by 22.5 moku. He had sente for most of the game (or so it felt to me) but I was able to gain a small advantage in a lower left corner invasion.

I just happened to have been browsing Haruyama's and Nagahara's section on tesuji in the corners just before the game (Basic Techniques of Go). That, plus my experience with pins (as Alan described my previously missed opportunities on Thursday) helped me think through the moves and build a living group while capturing a cluster of black stones.

It's cliché but it's worth repeating. You can learn a lot from your lost games.