If I remember the scene correctly, general grievous used fear before facing the jedis, leading one of them to a panic state, and when you are in fear, the last thing you do is think.

Correct. The situation was entirely different, too. This was Greivous's first public appearance, none of the Jedi had ever encountered him before--his attacks were so overwhelming they didn't have time to do anything other than survive. By the time Mace Windu encountered him, he had become infamous. On top of this, Windu is a far more focused and powerful jedi--the chaos of combat is actually what he draws his strength from, so he's uniquely qualified to fight him.