I don't. Grievous was trying to hit him, not just hitting his lightsaber, Dooku was barley trying to do anything but defend and tell him what he did wrong. Because he is a mentor to him doesn't mean he won't try to hit him, cause that's what he did. Thing is that Dooku knew almost exactly everything that Grievous could do, he could toy him with the force obivousley, and his defence wasn't even threatened by Grievous hits.
The only difference a real battle would make is Dooku going all out, and then Grievous is toast....
I remember Dooku saying "to defeat the best of the jedi, you must have fear, surprise and intimidation on your side, you must break them before you engage them". As far as I know, Dooku is in the TOP of the jedi in the order (though he is a sith), he had the advantage of traning him and offencive force powers. He will make short work out of Grievous....