And in primetime, CBS opens May sweep a winner

A wet track couldn’t dampen interest in the Kentucky Derby, as Saturday’s running on NBC delivered its highest overnight rating in 18 years.

The victory by Super Saver in the first leg of horse racing’s Triple Crown is also expected to stand as one of the week’s top five most-watched telecasts — behind only “Dancing With the Stars,” “American Idol” and perhaps “NCIS.” Final total viewer tallies won’t be available until Tuesday.

According to Nielsen overnights, though, NBC Sports’ coverage of the Derby averaged a 10.3 rating/23 share in the metered markets, up a tick vs. last year (10.2/22) and up 7% vs. 2008 (9.5/21). This is the best preliminary number for the late-afternoon event since 1992 (a 10.9/23 on ABC).

Last year’s race ended up averaging 16.3 million viewers in the nationals — a 20-year high — and this year’s is expected to be in that range, if not a bit higher.

NBC will also carry the final two legs of the Triple Crown: the Preakness Stakes on May 15 and the Belmont Stakes on June 5.

Elsewhere on the ratings front, CBS opened the May sweep on a strong note, rising vs. last year and overtaking ABC, which had kicked things off as the demo leader a year ago. While CBS (3.4/10 in 18-49) was up 13% vs. last year, ABC, NBC and Fox all declined by between 10% and 15%.

Nielsen same-night nationals for Thursday show CBS’ “Survivor” as the No. 1 program in 18-49 (4.1/13) and 25-54 (5.2/15), growing 14% vs. last year. At 9, “CSI” (3.0/9, 13.63m) was down 19% vs. last year, but “The Mentalist” (3.2/10, 14.84m) was a big 39% improvement over a repeat “Criminal Minds” a year ago and easily led the 10 o’clock hour.

All three CBS programs easily led their hours in total viewers.

ABC opened with “FlashForward” (1.6/5, 5.17m), which was down 20% from last year’s “Ugly Betty.” It was followed by “Grey’s Anatomy” (3.8/11. 10.47m), which tumbled 25% year to year but still led its hour in 18-49 and 25-54.

NBC’s entire lineup dipped a bit vs. last year, though top show “The Office” (3.6/11, 7.01m) held up best, tying at 9 o’clock for the 18-49 lead and leading in 18-34. And at 10, “The Marriage Ref” (1.9/6, 4.37m) was down a tick vs. last year’s “Southland.”

Fox’s “Bones” (2.6/7, 9.28m) was up vs. its May 2009 opener, but “Fringe” (2.0/6, 5.55m) was well below last year’s “Kitchen Nightmares.”

Similarly, CW was up at 8 with “The Vampire Diaires” (1.6/5, 3.39m) vs. “Smallville,” but “Supernatural” (1.1/3, 2.38m) lost some ground. For the evening, the net joined CBS as an opening-night gainer.

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