NEW YORK (AP) – Anchor changes at ABC's two biggest newscasts did nothing during their first week to shake NBC's dominance in the ratings.

NBC's 'Nightly News' with Brian Williams averaged 9.37 million viewers on the first week that Diane Sawyer anchored ABC's 'World News'. The ABC broadcast averaged 8.56 million viewers. Sawyer had just under nine million viewers for her first newscast, while Williams had 9.7 million viewers that day, the Nielsen Co. said.

NBC's 'Today' show also won easily during the first week for ABC's new 'Good Morning America' team of George Stephanopoulos and Robin Roberts.

Sawyer moved from 'Good Morning America' to 'World News' to replace the retired Charles Gibson. Stephanopoulos moved up from Washington to take her morning job.

'World News' averaged 500,000 more viewers last week than it has for a typical week this television season, while 'Nightly News' was up 440,000 (news viewership tends to increase during cold weather months). Compared to the same week last year, ABC is down slightly and NBC is up, Nielsen said.

"This is exactly where we expected to be and where we wanted to be," said Jeffrey Schneider, ABC News spokesman. "Both shows got bumps and put us on the right path."

Katie Couric got a much more dramatic increase during her first week on 'CBS Evening News', briefly lifting the show from third place to first. But that success, attributable largely to a publicity push that brought in curious viewers, did not last. ABC downplayed Sawyer's first week to avoid outsized expectations.

Last week, Couric's CBS newscast averaged 6.2 million viewers, Nielsen said. During Sawyer's debut week, ABC had its biggest lead over CBS in more than a year.

'Today', which hasn't lost a week in the ratings in more than a decade, averaged just under six million viewers, during Stephanopoulos' first week, while 'Good Morning America' had 4.6 million, Nielsen said. It was the most-watched week for 'Today' since March.

Both broadcasts were up eight percent from their season average.

It was a different story in prime-time, where CBS dominated a holiday week stuffed primarily with reruns and seasonal specials. NBC's telecast of Sunday night's NFL game between Dallas and Washington was the week's most watched programme.

CBS averaged 11.8 million viewers (7.3 rating, 12 share), and was second to Fox in the 18-to-49-year-old demographic that many advertisers seek. ABC had 9.3 million viewers (5.9, 10), Fox had 8.8 million (5.2, 8), NBC had 7.8 million (4.9, 8), the CW had 2.2 million (1.5, 2) and ION Television had 940,000 (0.6, 1).

A ratings point represents 1,149,000 households, or one percent of the estimated 114.9 million TV homes in the US. The share is the percentage of in-use televisions tuned to a given show.