As noted, WWE announced that Seth Rollins will be defending the WWE Championship against Sting at the Night Of Champions event on Sunday, September 20.
Rollins may be wrestling twice on that show. Based on the direction of last night’s Raw, it looks like Rollins will be defending the United States championship on that show against John Cena. Dave Meltzer noted on Wrestling Observer radio that Vince McMahon has not yet signed off on that match but it looks very possible for NOC.
On a somewhat related note, Sting is featured on some of the upcoming artwork that they will be using to promote the show. I saw one poster that shows Sting’s facepaint and the Night Of Champions logo on a poster.
For those that missed it, here is the WWE Network segment where Triple H announced Rollins vs. Sting for NOC: