maybe it was planned for Mace and Sidious to duel it out "mano-e-mano" in the end, but the way sidious was almost taken out, i'm leaning towards the idea that if anakin hadn't have distracted mace, sidious would have been done in.
Sure sidious took out the other Jedi that came after him, but if the duel were to have happened without Anakin interrupting it, Mace would have come out on top. It wasn't until Sidious had Anakin come to his aid, did sidious actually have the upper hand on mace, but, all it took was one lapse in concentration for things to go horribly wrong for mr. windu, and the galaxy to descend into darkness.
The very existence of flamethrowers proves that some time, somewhere, someone said to themselves, "You know, I want to set those people over there on fire, but I'm just not close enough to get the job done." -George Carlin