Fast National ratings for Friday, May 4, 2012.
 
Does CBS have an "Undercover Boss" problem? The reality hit started CBS' Friday with sluggish numbers, getting beat up by ABC's "Shark Tank" among young viewers. ABC, in fact, swept the night in the key demo, mirroring CBS' reliable overall Friday sweep.
 
Meanwhile, one of the problems with a couple weeks of slightly rising ratings for "Fringe" is that there actually was room for the already-renewed drama to fall. And it did, with a drop that has "The Avengers" written all of it.
 
Among adults 18-49, ABC averaged a 1.5 rating for the night, nipping the 1.4 rating for CBS in the key demographic. NBC averaged a 1.2 rating, followed by FOX's 0.9 rating and The CW's 0.5 rating.
 
Overall, though, CBS averaged an estimated 8.45 million viewers to go with a 5.5 rating/10 share to easily win Friday night. ABC was second with a 3.4/6 and 5.27 million viewers, with NBC's 3.2/6 and 4.87 million viewers good for third. FOX averaged a 2.1/4 and 3.41 million viewers in fourth. The CW did a 0.9/2 and 1.41 million viewers for Friday night.
 
8 p.m. - "Undercover Boss" started primetime in first for CBS with nearly 6.3 million viewers, but finished second with a 1.4 rating among adults 18-49, both down from last week. ABC's "Shark Tank" rose to 5.96 million viewers and a 1.7 key demo rating. NBC's "Who Do You Think You Are?" was third with nearly 4.9 million viewers and fourth with a 0.9 key demo rating. FOX's "The Finder? averaged 3.96 million viewers and a 1.0 key demo rating. The CW's "Nikita" did 1.24 million viewers and a 0.4 key demo rating, down a hair overall and flat in the key demo.
 
9 p.m. - "CSI: NY" kept CBS in first overall for the 9 p.m. hour with 8.95 million viewers and also kept CBS in second among adults 18-49 with a 1.3 rating. "Grimm" was a distant second overall with 4.7 million viewers for NBC and also posted a 1.3 key demo rating. ABC's "Primetime: What Would You Do?" averaged 4.69 million viewers for third, but won the hour with a 1.4 key demo rating. FOX's "Fringe" dropped to 2.85 million viewers and a 0.9 key demo rating in the season's penultimate episode. The CW's "Supernatural," newly renewed itself, averaged 1.58 million viewers and a 0.7 key demo rating.
 
10 p.m. - "Blue Bloods" averaged nearly 10.1 million viewers for CBS, winning the 10 p.m. hour overall, but coming in second with a 1.4 rating among adults 18-49. ABC's "20/20" was second overall with 5.17 million viewers and won the hour with a 1.5 key demo rating. NBC's "Dateline" was third with 5.025 million viewers and a 1.3 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.