If Heroes was Superman, then Joey Fatone just might be kryptonite.

The NBC series has had trouble taking off in the ratings since returning from spring break, and finding itself faced with Fatone and his Dancing with the Stars sidekicks.

On Monday, Heroes fell to 11.1 million viewers, compared to the night-best 19.1 million schmoozed by ABC's ballroom show, per Nielsen Media Research estimates.

Heroes was down from last week (21st place, 11.9 million), down from the week before that (17th place, 12 million), and quite a bit down from its season-to-date average (14.6 million).

By comparison, Monday's Dancing, featuring the moves of its final five couples, hit its biggest audience in six weeks.

Heroes continues to hold the edge in attracting advertiser-coveted 18-to-49-year-olds, although for a certified "It" show, its lead over a tuxedoed descendant of Lawrence Welk isn't as big as might be expected.

For most of its freshman season, Heroes didn't have to worry about being shown up by ex-'N Sync singers in satin shirts. It aired on Mondays; Dancing aired on Tuesday and Wednesdays. Then, in March, Heroes took a vacation. When it came back, on Apr. 23, the new season of Dancing was up and running with Heather Mills' one good leg, and airing on Mondays and Tuesdays. The shows typically go head-to-head on Monday from 9-9:30 p.m.

Heroes isn't the only Monday series whose powers have been zapped in recent weeks. Since Dancing's new season premiered on March 19, Fox's 24 has seen its season-to-date average shrink by more than 1 million viewers, from 14.6 million to 13.5 million. On Monday night, the show scored an estimated 10.9 million. (Like Heroes, 24 airs from 9-10 p.m., usually going up against the coattail end of Dancing.)

The 24 funk has been blamed on a literally tortuous sixth season; Heroes' has been blamed on its interminable six-week-long siesta. Neither is feared to be fatal—Heroes, in fact, was reupped for next season back in January. Though not officially renewed yet, 24 is also expected to live on.

As for Dancing with the Stars? Well, it took 27 years before Lawrence Welk retired. Kryptonite has a rather long shelf life.

Elsewhere, here are some ratings highlights from the TV week ended Sunday:

• Charity, schmarity. What American Idol fans want are mass executions. Wednesday's Phil Stacey-Chris Richardson double-elimination show averaged 28.8 million (first place), up nearly 2 million from the Idol Gives Back special.
• Idol's Bon Jovi performance night rocked (second place, 26.7 million), just not as hard as last year's current-hits performance night (28.6 million).
• If Idol wasn't its 2006 self, then neither was CBS' CSI (fifth place, 19 million—down from 26 million for the same week last year), Fox's House (fourth place, 21.1 million—down from 22.7 million), CBS' CSI: Miami (seventh place, 17.2 million—down from 19.3 million), ABC's Desperate Housewives (sixth place, 17.16 million—down from 21.3 million) and CBS' Without a Trace (10th place, 14.7 million—down from 19.1 million).
• ABC's Grey's Anatomy likewise got more play from a regular-old May 2006 episode (22 million) than for a two-hour blowout introducing Kate Walsh's would-be spinoff series (third place, 21.2 million).
• Among the top 25, only one show that was around this time last year was up, not down. The showoff: CBS' Criminal Minds (15th place, 13.3 million—up from 12.2 million).
• Cute-couple Eric and Danielle won CBS' The Amazing Race: All-Stars (29th place, 10.3 million); Ty Pennington crashed the party with a Sunday time slot win for ABC's Extreme Makeover: Home Edition (22nd place, 11.9 million).
• NBC's Deal or No Deal (36th place, 9 million) turned 100-episodes old on Sunday—and all it got was a third-place finish.
• NBC's ER (44th place, 7.8 million) threw a fancy wedding, and all it got was left in the dust by Grey's Anatomy.
• Medium (47th place, 7.7 million) has been renewed for next season because, per NBC Entertainment president Kevin Reilly, it's "a quality show with an outstanding star," and presumably not because it's down nearly 25 percent in viewers from last season.
• The test results are in: "Laugh 'n' Sniff" My Name Is Earl (50th place, 7.6 million) is just as viewer-challenged as odor-free Earl.
• NBC's The Real Wedding Crashers (67th place, 5.6 million) is doing its best to make Studio 60, if not The Black Donnellys, look good by comparison.
• The CW's Gilmore Girls (89th place, 4.1 million) isn't talked out yet; 7th Heaven (108th place, 2.9 million) pretty much is.
• Not to beat a dead horse, but Barbaro is no prime-time player, as NBC learned Saturday with its hourlong special about the late Kentucky Derby winner (99th place, 3.3 million).
• Wonder if free agent Rosie O'Donnell wants to anchor the CBS Evening News, last seen dropping to its least watched week on record (6.1 million). 
• In cable, MSNBC's Republican Presidential debate (1.8 million) was outpolled by the previous week's Democratic showdown (2.3 million).

Overall, in sweeps-week action, CBS was the most watched network, averaging 11.2 million viewers; Fox was the highest rated network among young adults.

Blown out from Friday-Sunday, Fox fell to third in viewers (10.1 million). Failing to tempt enough youngsters to its non-CSI shows, CBS fell to third in the demo.

ABC (10.7 million) notched a pair of second-place finishes; NBC (7.5 million) a pair of distant fourth-place ones. The CW (3.1 million) was in a little class by itself.

Here's a look at the 10 most watched prime-time shows for the week ended Sunday, according to Nielsen Media Research:

1. American Idol (Wednesday), Fox, 28.8 million viewers
2. American Idol (Tuesday), Fox, 26.7 million viewers
3. Grey's Anatomy, ABC, 21.2 million viewers
4. House, Fox, 21.1 million viewers
5. CSI, CBS, 19 million viewers
6. Dancing with the Stars (Monday), ABC, 18.97 million viewers
7. CSI: Miami, CBS, 17.2 million viewers
8. Desperate Housewives, ABC, 17.16 million viewers
9. Dancing with the Stars (Tuesday), ABC, 16.3 million viewers
10. Without a Trace, CBS, 14.7 million viewers