Fast National ratings for Wednesday, August 20, 2014.

"Big Brother" ranked as Wednesday's top show among young viewers and helped CBS win the night in that measure, while "America's Got Talent" led NBC to an overall victory.

CBS' double-dose of "Extant" was roughly consistent with recent airings and beat "Taxi Brooklyn" overall in the 10 p.m. hour. 

Among other notables, FOX's "So You Think You Can Dance" slipped again, while The CW's "Penn & Teller: Fool Us" rose again, though both variations were relatively miniscule.

On to the numbers...

Among adults 18-49, CBS averaged a 1.4 rating for Wednesday night, edging out NBC's 1.3 rating in the key demographic. ABC and FOX both averaged a 0.9 key demo rating, while The CW averaged a 0.4 key demo rating. 

Overall, though, NBC averaged an estimated 6.57 million viewers and a 4.2 rating/7 share for Wednesday primetime, beating CBS' 5.91 million viewers and 3.7/7. ABC averaged 3.55 million viewers and a 2.4/4 for the night, followed by FOX's 2.2/4 and 3.36 million viewers. The CW averaged 1.09 million viewers and a 0.7/1.

8 p.m. - "Big Brother" started primetime in first with 6.58 million viewers and a 2.3 rating among adults 18-49 for CBS, up a little from last week. NBC's "America's Got Talent" encore was second with 5.6 million viewers and a 1.1 key demo rating. FOX's "So You Think You Can Dance" averaged 3.52 million viewers and a 0.9 key demo rating, compared to the 0.9 key demo rating and 3.17 million viewers for ABC's repeats of "The Middle" and "The Goldbergs." The CW averaged 1.72 million viewers and a 0.6 key demo rating, a series high in the key demo.

9 p.m. - "America's Got Talent" controlled the 9 p.m. hour for NBC with 9.19 million viewers and a 1.8 rating among adults 18-49, down from last week in viewers. CBS' "Extant" averaged 5.505 million viewers for second and a 1.0 key demo rating for third, compared to the 3.69 million viewers and 1.2 key demo rating for ABC's pair of "Modern Family" repeats. FOX's "So You Think You Can Dance" averaged 3.21 million viewers and a 0.9 key demo rating. On The CW, a repeat of "The 100" averaged 467,000 viewers and a 0.2 key demo rating.

10 p.m. - "Extant" closed primetime in first with 5.65 million viewers and tied for the hour lead with a 0.9 key demo rating. NBC's "Taxi Brooklyn" was second overall with 4.93 million viewers and tied for the lead with a 0.9 rating among adults 18-49. ABC's "Motive" averaged 3.8 million viewers and a 0.8 key demo rating.

All ratings information comes from preliminary Fast National Nielsen data, which includes live and same-day DVR viewing. All numbers are subject to change.