CBS scored a clean sweep among young and old viewers during the third week of the new television season, while ABC showed signs that its two freshman successes may have staying power.

Meanwhile, problems deepened at NBC and Fox, based on Nielsen Media Research (search) rankings.

"CSI: Crime Scene Investigation" (search) was easily the week's most popular program, with 28.4 million viewers. All three of CBS's Thursday night entries finished in Nielsen's top five -- a night that NBC owned for many years.

CBS also won the week among viewers aged 18 to 49, the demographic group advertisers watch most closely. Even though CBS has been the most popular network overall the past two years, its inability to beat NBC among young viewers has hurt its bottom line.

ABC entered the season a fourth-place network with no bona fide hits. That's quickly changed, with "Desperate Housewives" (search) (20 million viewers) and "Lost" (search) (16.5 million), retaining a high percentage of their audiences last week after impressive debuts.

The lineup of "Extreme Makeover: Home Edition," "Desperate Housewives" and "Boston Legal" has suddenly made ABC the leader on Sunday nights.

NBC sank to third last week behind CBS and ABC among 18-to-49-year-old viewers. "ER" was its only program among Nielsen's top 10, and even that lost its time slot to CBS's "Without a Trace."

NBC averaged 11.4 million viewers for the first three weeks of the 2003 season, and that's dropped to 10.1 million this year -- again, narrowly behind ABC.

Fox has virtually nothing to brag about. Its season average of 6.2 million viewers is a steep drop from last year's 9.8 million at a similar point. With the baseball playoffs and World Series, Fox has held off some of its high-profile programming until November -- but that was the case last year, too.

For the week, CBS averaged 13.8 million viewers (9.0 rating, 15 share), NBC had 9.9 million (6.5, 11), ABC had 9.7 million (6.4, 10), Fox had 7.8 million (5.2, 9), the WB had 4 million (2.7, 4), UPN had 3.7 million (2.5, 4) and Pax TV had 570,000 (0.4, 1).

NBC's "Nightly News" won the evening news ratings race, averaging 9.7 million viewers (6.9, 15). ABC's "World News Tonight" had 8.4 million viewers (5.9, 12) and the "CBS Evening News" had 6.7 million (4.8, 10).

A ratings point represents 1,096,000 households, or 1 percent of the nation's estimated 109.6 million TV homes. The share is the percentage of in-use televisions tuned to a given show.

For the week of Oct. 4-10, the top 10 shows, their networks and viewerships: "CSI: Crime Scene Investigation," CBS, 28.4 million; "Without a Trace," CBS, 21.3 million; "CSI: Miami," CBS, 20.7 million; "Desperate Housewives," ABC, 20 million; "Survivor: Vanuatu," CBS, 19.5 million; "Everybody Loves Raymond," CBS, 17.4 million; "ER," NBC, 17.1 million; "CSI: NY," CBS, 16.9 million; "Lost," ABC, 16.5 million; "Two and a Half Men," CBS, 16.4 million.