It was a battle of two "Americal Idol" winners, and Kelly Clarkson came out on top. Clarkson's single "Stronger" topped Carrie Underwood's "Before He Cheats" as the best-selling single ever from an "Idol" competitior. "Stronger" broke the record on July 4, outselling "Before He Cheats" by 1,000 copies, and is also Clarkson's longest-running No. 1 single.