I'm referring to Labyrinth of Evil, which coincidentally directly contradicts the events of the 2003 series. Grievous fights Windu on the back of a Mag-lev train, and while he's able to analyse and produce something resembling Vapaad, it isn't Vapaad, and Windu easily defeats him. Even in the 2003 series Dooku directly warns Grievous about the better duelists in the Jedi order.
Probably my favorite line in the episode 3 novelization is when Grievous spouts his "I was trained in the Jedi arts by count dooku" spiel and Obi-wan replies by saying he trained the man who killed him.