Hego Damask wins round 1. He might not be as renowned a swordsman as Dooku is, but he is far faster and stronger and would have Tyranus on the defensive immediately, and then he'd just exhaust the Count before breaking his bones.
Plagueis in an earth-shattering stomp for round 2.
Plagueis again in round 3. It's only a fight because Dooku will have the fortune of Plagueis dueling him first before humiliating him with Force powers. Although with bloodlust, it's probably just round 2 all over again.