• by Wayne Friedman , February 19, 2014

NBC Olympics prime time numbers dipped under the 20 million viewer level for the first time on Tuesday -- the tenth day of the big sporting event.

NBC Olympic programming -- featuring women’s bobsled, women’s giant slalom, men’s ski half-pipe, short track-- posted a Nielsen preliminary 18.5 million viewers. This is under NBC’s Sochi Olympic average audience of over 21.5 million so far.

NBC also posted 4.8 rating/14 share among 18-49 viewers -- down 27% from last Tuesday’s 6.6 rating and off 11% from the 13th night of the 2010 Vancouver Winter Olympics.

On Monday night, the event -- featuring a gold medal-winning ice-dancing performance by U.S. skaters Meryl Davis and Charlie White -- posted big 23.5 million viewers and a 5.6 rating/15 share among 18-49 viewers. That's a 12% improvement over the 20.9 million viewers for the second Monday of the Vancouver Olympics in 2010.

Broadcast networks didn’t shy away from offering competition -- led by Fox’s “American Idol,” which pulled in 9.6 million viewers and a 2.7/8 among 18-49 viewers. That said, “Idol” was down 10% from its 3.0 18-49 rating of a week before. A CBS rerun of “NCIS” posted 9.8 million viewers and a 1.3/4 in 18-49.

ABC continues to see weak results for its new 10 p.m. drama “Killer Women,” now at a small 3.2 million viewers and a 0.6/2 among 18-49 viewers .