Are Madonna's first-week sales numbers a disappointment? Blame Mariah.

While Madonna scored yet another No. 1 album, it may not have been the blockbuster opening that some were expecting.

She sold 280,000 copies of "Hard Candy," according to Nielsen SoundScan, in its first week in stores. First things first: With the days of the CD as the music format of choice seemingly numbered, any album that sells in the six-figure range is a bonus for the music biz these days.

And those who rolled their eyes at yet another blog alluding to the death of the CD, ask Madonna herself, who last year signed a $120-million deal with a touring company in Live Nation. And this summer, fans will get to see that deal start paying off. Madonna will be generously coming to a whopping 16 North American markets, according to Billboard.

Great Diva Sales Race of 2008

Yet it's also hard not to note that Madonna's "Hard Candy" sold about 180,000 copies less than Mariah Carey moved two weeks ago. She's still significantly ahead, though, of the 181,000 copies sold by Janet Jackson's "Discipline" when it debuted in March.

But back to Carey. Her "E=MC2" scored the highest debut of the year when it opened at No. 1 after selling 463,000 copies. In just three weeks on the chart, "E=MC2" has sold more than 740,000 copies.

Album sales may be down across the board, but Madonna would certainly be expected to be closer to Mariah than, say, Leona Lewis, on the diva totem pole. Newcomer Lewis entered at No. 1 a few weeks ago, her debut, "Spirit," selling 205,000 copies.

To compare "Hard Candy's" stats to Madonna's last record: in 2005 her Euro-influenced "Confessions on a Dance Floor" opened with 350,000 copies, according to Billboard. It's rare these days for an artist to actually top the first-week sales of a prior album, but if anyone could do it, it would certainly be Madonna. And Mariah just did it.

So it's easy to view Madonna's sales tally as a disappointment, a sign that she's losing her grip on the pop marketplace. But don't.

CD sales just an added bonus

Billboard downplays Madonna's sales dip, noting that "Confessions" opened during the holiday season. The trade also fairly points out that Mariah may have benefited from appearances on "The Oprah Winfrey Show" and "American Idol."

On one hand, Madonna is a bigger international brand than Mariah will ever be, and she was just inducted into the Rock and Roll Hall of Fame.

But on the other, the marketing campaign for "Hard Candy" was one based less on promotion than it was partnerships. The album may not have been endorsed by Oprah, but the marketing campaign leading up the release of "Hard Candy" has been far from what anyone would call subtle. There's the Sunsilk commercials, the branding promotions with Verizon, the odd YouTube video and the video gift to gossip blogger Perez Hilton.

Additionally, Madonna's lead single "4 Minutes" has been inescapable. It's still a top-10 hit, and her second single, "Give It 2 Me," has just debuted inside the top-100. But even more important, "4 Minutes" has given Madonna something she didn't have at all with "Confessions on a Dance Floor," and that's a hit on U.S. radio.

But if there's a problem -- if this is a problem -- with "4 Minutes," it's that it is as much a Justin Timberlake or Timbaland single as it is one from Madonna. It's also a song that will spur download sales, but not necessarily album sales.

For instance, as fun and silly as it may be, "4 Minutes" also could have appeared on Timbaland's 2007 album "Shock Value," or Timberlake's "FutureSex/LoveSounds." It's a song fit for an iTunes playlist as much as it is a new Madonna album.

Indeed, by lining up today's top producers and superstars -- Timberlake, Timbaland, Pharrell Williams, Kanye West, etc. -- Madonna has created an album that may sound swell stacked up with everyone else on the radio, but it also risks the danger of failing to set itself apart.

But "Hard Candy" doesn't really need to stand alone in order to be a success. The end result is an album seemingly built to sell millions of single-track downloads, ring tones, videos and bits of whatever digital accessories exist. And for pop music as business plan, that may prove to be one of Madonna's smartest moves yet, whether intentional or not.