Yahoo sued Facebook for patent infringement on Monday, claiming Facebook infringed ten patents related to online advertising, instant messaging and other technologies.

This is a defining moment for both companies. Yahoo is the old lion desperately trying to remain relevant by challenging the younger and stronger Facebook. Facebook is about to step into the public company spotlight, unless its upcoming IPO gets derailed.

The reaction to the lawsuit shows yet another sign that Yahoo's grasp on the tech and advertising industries is weak. Did the Lion in Winter realize how severely it would be crushed in the court of public opinion?