Weapon Master Mace Windu could very well be the second greatest duellist in the entire Star Wars EU, behind Grand Master Luke Skywalker, Count Dooku was an excellent duellist and possibly the greatest of all Makashi practitioners, but Mace Windu took on the most powerful Dark lord of the Sith ever, Darth Sidious, and beat him in a duel, which is in fact the only one on one battle Sidious ever lost, Count Dooku would never be able to defeat Sidious, He was a master duellist but not on the same level as Windu.
Really? I'm not trying to dismiss your answer, I like it, but I think I've heard, or read, that Sidious purposely withdrew from that 1 on 1 battle in order to better turn Anakin, to make Windu seem like the bad guy for striking down a defenseless opponent.
Did Sidious really lose, or did he sense Anakin's arrival and planned to turn him at that moment? Even without the saber he wasn't defenseless.