actually I was annoyed in jedi academy that you could not face the rancor and do damage to it, I had a plan all set, it involved 8 thermal detonators and a load of force lightning, with a side dose of a missile launcher and a disruptor rifle. That thing would have been dead, but no, I "couldn't hurt it" bs.
I say that the jedi could win, Luke in RotJ when he was still basically a padawan took on a rancor without a lightsaber, 2 jedi masters with lightsabers could surely defeat a mutated rancor. Besides, even if the rancor was invincible, it would get so tired watching Yoda flip around it, it would fall asleep and then the jedi could cut off its head.