This is very illogical ... relook at the movie carefully .... firstly to say that Palpatine was faking the fight because he KNEW Anakin was going to arrive and kill Mace is really really illogical ... because there are so many possibilities for things to get screwed up in this plan ... first of all, what if Anakin had arrived on the scene 60 seconds later than he did ?
It's unambiguously clear that Mace had defeated him .... he clearly and unambiguously had his lightsabre at a prostrate Palpatine's throat, and ALL of Palpatine's lightning wasn't enough to knock him off or make him retreat ... he took all that lightning and reflected it back ... now ... if at THIS moment Anakin wasn't there .... Palpatine would have been killed ... that is totally UNAMBIGUOUS .... to state that Palpatine wasn't using his full power is folly .... because he is depending on TWO factors that could go either way for or against him ... ONE : That Anakin arrives on time ... and TWO : He makes the decision to injure Mace Windu and stop him from finishing Palpatine off .... both these factors could go either way .... we definitely see Anakin's conflict inside himself ... he isn't totally ready to kill Mace until the very last second ... and even after he had injured Mace ... he still is filled with remorse ...
Palpatine's character is a master manipulator like a clever chess player ... it would be folly to suggest that he would risk the success of his whole scheme on two factors that could as easily go against him as for him ... the fact of the matter is ... like Chilled Monkey said ... this movie is about Anakin's choices .... if his choice had been the opposite to what he actually does in the story ... than it is quite UNAMBIGUOUS in the movie that Palpatine would have been killed by Mace Windu at that moment ... there is no doubt that he was defeated and bested by Windu and only survived that moment because of Anakin's turn to the dark side ... that in fact is the central theme of this whole 6 part movie series ... to miss this is to miss the main point. To not understand and accept that it was Anakin's decision at that last moment before Sidious was about to be sliced in half by Windu ... that ultimately sealed the fate of the Jedi is to miss the point of the whole STAR WARS series and the prequel trilogy .... it's not about Darth Sidious being invincible and the most powerful ... because that is simply not true ... it is about the corruption of Anakin Skywalker and his wrong choices, that leads to the extermination of the Jedi, who are essentially betrayed by him ... and the beginnings of the reign of the darkside in the galaxy ... this is the point of the whole tale .... but to fail to see that Mace Windu was clearly superior to Darth Sidious and had him beaten is to be blind ... Also ... there was no doubt that Yoda was superior to Darth Sidious in their duel .... just barely superior no doubt ... but definitely superior ... again there is no doubt that the only reason that Darth Sidious did not take the pains to continue the fight with Yoda was because it was clearly apparent, that had the duel continued .... he would have sooner or later been defeated and killed by Yoda. I think Lucas has made both these aspects very clear .... because he himself is very clear on this point ... THE DARK SIDE IS NOT MORE POWERFUL ... IT IS VERY POWERFUL NO DOUBT ... BUT IT IS NOT MORE POWERFUL THAN THE LIGHT SIDE ... AND THEREFORE THE MOST POWERFUL AND ENLIGHTENED JEDIS ( IN THIS CASE MACE WINDU AND YODA ) WILL ALWAYS BE MORE POWERFUL THAN THE SITH IN SINGLE COMBAT .... and Lucas makes this very clear in THE EMPIRE STRIKES BACK, when Yoda is teaching Luke. And I think he has made this clear in this movie as well quite unambiguously ... Mace Windu was more powerful than Darth Sidious ... and had him defeated and helpless ... he lost not because of Sidious's superiority, but because he was caught off guard by Anakin ... and because he never expected Anakin to betray him .... similarly ... Yoda failed to kill the sith lord not because of the sith's superiority ... but because of the unnatural way and circumstances in which that battle was cut short .... Darth Sidious was clearly shown to throw everything he had at Yoda ... and all of it wasn't enough ... Yoda took it all and gave it back to him worse than he got ... I can't believe that as UNAMBIGUOUS as all of this is on screen, there is any kind of debate on this issue.