Nine years ago, ABC brass were ready to dump Nightline for David Letterman. Boy, aren’t today’s bigwigs at the company happy that didn’t happen. The veteran ABC newsmagazine beat both CBS’ Late Show With David Letterman and NBC’s The Tonight Show With Jay Leno among adults 18-49 during premiere week for the first time ever. Nightline, which airs from 11:35 PM-midnight, saw its audience grow 7% vs. last fall to 3.9 million. In adults 19-49, it averaged 1.3 million, even with last year. Its companion, Jimmy Kimmel Live was also strong out of the gate, drawing its second-largest premiere week audience ever (1.8 million) and 790,000 adults 18-49, up 5%.

http://www.deadline.com/2011/09/nbc-cbs-late-night-lineups-down-in-premiere-week-abc-on-the-rise/

They won a single week. How does that make them "the new kings", LOL?