Hilary Duff and her boyfriend, Good Charlotte frontman Joel Madden, take the stage in their first TV appearance together to introduce best new artist winners The Killers, who performed "Mr. Brightside." Duff tells PEOPLE that Madden's recent assertion that she is the "greatest singer today" was misstated. "I think it came up on MTV News," she says. "He probably said 'one of the best.' I know I'm not the best singer around."