The big ratings surprise this week wasn’t the final episodes of “American Idol” or “Dancing With the Stars.”

It turned out to be “Nightline,” which drew nearly 7 million viewers Tuesday night with its long-awaited, first interview with Jessie James, the cheating husband of Sandra Bullock.

“Nightline” crushed David Letterman and Jay Leno combined — and snared the largest rating the show has had since Ted Koppel left in 2005.

In fact, it was the show’s biggest night since March 21, 2003 — the first day of the Iraq war.

ABC delayed airing the James interview with Vicki Mabrey until the night of the “Dancing” finale — to give itself the biggest possible lead-in audience.

During the interview, which was heavily promoted, James — a motorcycle maker and TV personality — admitted he made a huge mistake cheating on his popular movie-star wife and, at one point, walked off camera when he began to tear up.