Kelly Clarkson Filling In for Simon Cowell on 'AGT' After Back Injury. One 'AI' alum replaces another on "America's Got Talent" ... temporarily. Another "American Idol" alum is going to fill Simon Cowell's shoes while he recovers from his broken back Kelly Clarkson's stepping into the spotlight for "America's Got Talent." Kelly herself made the announcement Monday with a mock 'AGT' memo sent to "All Staff." It reads, "My friend, Simon Cowell, is doing better now but was in an accident and won’t be able to make Tuesday and Wednesday’s live shows for AGT, but no worries America, someone far wiser, cooler, and hotter is taking his seat!" This is going to be interesting check out the link to read the full story.