Ash Can't, Um, Bump Mariah, Leona or Conchords

Simpson's Bittersweet World manages only No. 4 debut, behind Carey, Lewis and new release from Flight of the Conchords

A high-profile engagement, endless speculation about major uterine developments and plenty of face time on TV and magazines couldn't put Ashlee Simpson over the top.

As it were, Jessica's baby sister managed just a bittersweet No. 4 debut for Bittersweet World, failing to extend her run of chart-topping albums and looking up at Mariah Carey, Leona Lewis and even the New Zealand novelty act Flight of the Conchords.

Carey and Lewis pulled a Groundhog Day in the top spots. Despite a 61 percent sales drop, Carey's E=MC2 remained No. 1, selling another 182,000 copies for the week ended Sunday, per Nielsen SoundScan, while Lewis' Spirit held down the No. 2 spot, selling 96,000. Conchords, meanwhile, held off Simpson for the week's top debut.

The Kiwi comedy-music duo had only managed a No. 116 bow with last August's The Distant Future EP, but following a 2008 Grammy win and praise for their eponymous HBO series, Flight of the Conchords has officially taken off. The group's self-titled debut finished the week ended Sunday at No. 3 on 52,000, per Nielsen SoundScan numbers, ahead of Simpson's World, which spun 47,000 copies.

Simpson, who sources tell E! News is preggers with new Fall Out Boy fiancé Pete Wentz's spawn (the couple has been coy about whether there is a bun in the oven), had both her previous albums debut at No. 1, thanks to hit singles like "Pieces of Me" and "Boyfriend." But the beat-driven World—featuring production by star-makers Timbaland, the Neptunes' Chad Hugo and Kenna—has yet to have a track crack the Hot 100, going 0-2 so far with "Outta My Head (Ay Ya Ya)" and "Little Miss Obsessive."

Hip-hop duo Slug and Ant, better known as Atmosphere, sold 36,000 copies of When Life Gives You Lemons... to squeeze out a No. 5 bow. Phil Vassar—who penned hit songs for others before becoming a country star himself—followed at No. 10, selling nearly 27,000 copies of Prayer of a Common Man.

Outside the top 10, other notable debuts included Story of the Year's Black Swan at No. 18, the Weepies' Hideaway at No. 31 and Mobb Deep rapper Prodigy's H.N.I.C. Pt. 2 at No. 36.

Overall, the numbers were down 8 percent from last week's Mariah-powered sales, and down 11 percent compared to the same week in 2007.

A rundown of the top 10:

1. E=MC2, Mariah Carey
2. Spirit, Leona Lewis
3. Flight of the Conchords, Flight of the Conchords
4. Bittersweet World, Ashlee Simpson
5. When Life Gives You Lemons..., Atmosphere
6. Now That's What I Call Music! Vol. 27, various
7. Juno soundtrack, various
8. Troubadour, George Strait
9. Taylor Swift, Taylor Swift
10. Prayer of a Common Man, Phil Vassar