With a full day's worth of sales under its belt, Jay-Z & Kanye West's new "Watch the Throne" album is projected to sell over 500,000 copies in its first week in the U.S., according to industry sources. That's above initial estimates yesterday, where prognosticators placed the set's debut week sales somewhere in the range of 400,000 - 500,000 copies.

The dynamic duo's album was released exclusively via Apple's iTunes Store yesterday, Aug. 8.

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The album is on track to become the second-largest sales week of the year, behind Lady Gaga's 1.1 million opener for "Born This Way."

"Watch" will easily top the Billboard 200 chart next week (which will be revealed on Aug. 17), unless something completely unexpected happens. The album will mark the 12th No. 1 album for Jay-Z and the fifth for West. Jay has previously topped the list with two other collaborative albums: "MTV Ultimate Mash-Ups Presents: Collision Course" with Linkin Park, and "Unfinished Business" with R. Kelly.

"Watch the Throne," which incredibly didn't leak to the Web as so many eagerly-awaited albums have over the years, is exclusive to iTunes until Friday, Aug. 12. That's when all other retailers -- physical and digital -- will start selling "Watch." Of course, most brick-and-mortar retailers could opt to ignore the official street date and begin selling the CD as soon as they receive it, which may be as early as Wednesday.

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Best Buy has the exclusive deluxe physical CD edition of the set from Aug. 12-22, which sports the same four additional songs as on iTunes' deluxe version. These exclusives have angered many retailers who were excluded from the promotions.

Predicting "Throne's" first week is tricky because of its unique release rollout. Traditionally, albums drop to all retailers on Tuesdays. However, "Throne" secured a Monday street date -- but only through iTunes. So, its first four days of release will consist mostly of sales via Apple (with physical street-date violation sales mixed in), while the remaining three days of its first week will be a blend of physical and digital.

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Thus, because of the unusual nature of "Throne's" release, stay tuned through the week for further news on its first-week sales pace.