Today's daily "diabolical" puzzle at this link:
http://www.palmsudoku.com/pages/s-o-t-d.php?day=0&level=5
shows how to solve the puzzle step by step (which is a fantastic learning tool) however, unless I am mistaken, the 1st forcing change shown in the solution does not appear to be a forcing chain at all. The only way I can see to proceed is to use the Nishio technique. If anyone gets a chance, would you mind taking a look and letting me know what you think. Thanks much.