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If you take a look at the card for Night of Champions, there aren't many opportunities for "Holy $#!^" moments. We have Sheamus and Del Rio (again), Kaitlyn and Layla (bathroom/snack break), Dolph Ziggler and Randy Orton, and then Intercontinental, U.S., and Tag Team championship matches that haven't been announced yet.
On that card, the only other real contender for a show stealer is Ziggler. Ziggler and Orton will be a great match (my match of the night prediction) and has the opportunity to outshine the others. However, the fact that it isn't for any gold and there isn't much of a story to go along with it, hurts it's show-stopping chances.
Punk is athletic enough that he can steal the show with a big spot in the ring. He has the most interesting storyline going right now, which has the potential to affect the match with the possibility of Heyman's involvement.
The only way I see that anyone can steal the show from Punk is if Wade Barrett shows up and wrecks the show for Sheamus. That seems unlikely after his squash match against Yoshi Tatsu or if Ziggler finally cashes in his Money in the Bank briefcase to bring some new life to the Smackdown title.