NEW YORK (AP) - ABC's ''Duel'' was a dud, but a good-natured singing competition on NBC engaged more television viewers in the week leading up to Christmas.

None of the six editions of ''Duel'' that aired in prime-time for ABC last week reached over 7.5 million viewers. The last show on Sunday, billed as the week's climax, was the least-watched, with 6.2 million viewers, according to Nielsen Media Research.

Each of the four episodes of NBC's ''Clash of the Choirs'' did better. The best night of the series that featured celebrities cobbling together singing groups had 8.3 million viewers, Nielsen said.

NBC's two-hour ''The Biggest Loser 4'' on Tuesday had 11.4 million viewers, helping the network win the week among the 18-to-49-year-old demographic that advertisers crave.

With television viewers otherwise occupied, the week's most popular prime-time event - the Sunday night football matchup of Washington and Minnesota - had only 14.1 million viewers, Nielsen said.

CBS averaged 8.6 million viewers for the week (5.6 rating, 10 share), NBC had 7.5 million (4.9, 8), ABC had 5.9 million (3.8, 7), Fox had 5.6 million (3.5, 6), the CW had 2 million viewers (1.3, 2), My Network TV had 1.3 million (0.8, 1) and ION Television had 590,000 (0.4, 1).

Among the Spanish-language networks, Univision led with 3.1 million viewers (1.6 rating, 3 share), Telemundo had 1 million (0.6, 1), TeleFutura had 630,000 (0.3, 1) and Azteca had 120,000 (0.1, 0).

NBC's ''Nightly News'' dominated the evening news ratings race, averaging 9.3 million viewers (6.2 rating, 12 share). ABC's ''World News'' had 8.6 million (5.9, 12) and the ''CBS Evening News'' had 6.3 million (4.3, 8).

A ratings point represents 1,130,000 households, or 1 percent of the nation's estimated 112.8 million TV homes. The share is the percentage of in-use televisions tuned to a given show.

For the week of Dec. 17-23, the top 10 shows, their networks and viewerships: ''Sunday Night Football: Washington at Minnesota,'' NBC, 14.1 million; ''CSI: Miami,'' CBS, 14.01 million; ''60 Minutes,'' CBS, 13.52 million; ''NCIS,'' CBS, 13.01 million; ''Criminal Minds,'' CBS, 11.66 million; ''The Biggest Loser 4,'' NBC, 11.42 million; ''Two and a Half Men'' (Monday, 9:30 p.m.), CBS, 11.28 million; ''CSI: NY,'' CBS, 10.3 million; ''Two and a Half Men'' (Monday, 9 p.m.), CBS, 11.1 million; ''The Unit,'' CBS, 10.74 million.

By DAVID BAUDER AP Television Writer

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