TUESDAY SEPTEMBER 26, 2006 01:55PM EST

By Tim Nudd

people.com

Katie Couric suddenly finds herself in an unfamiliar spot: No. 2 in the ratings.

After a fortnight of viewership victories, Couric and the CBS Evening News ceded the top spot last week to its more common holder, NBC's Nightly News with Brian Williams, according to estimates released Monday by Nielsen Media Research.

For the week, CBS averaged 7.7 million viewers, behind NBC's 8.2 million but ahead of ABC's 7.6 million for World News with Charles Gibson.

Couric's big opening night three weeks ago drew 13.6 million viewers. Her ratings are down 24 percent since the first week but are still ahead of last year's numbers.

For Couric, 49, being No. 2 is uncommon ground. In the decade before she left NBC, her Today show consistently dominated the morning-news ratings.

NBC Universal chairman Bob Wright was in a celebratory mood Monday during an Advertising Week event at the Museum of Television & Radio. "Brian is back where God wanted him to be, at No. 1," he joked, according to The Hollywood Reporter.

Wright said NBC wanted to keep Couric before she left for CBS in the spring. With Williams solidly in the NBC anchor chair, Wright said the network explored the idea of a possible syndication window for a Couric show. But "she never really raised her hand to go in that direction," he said.