Radiohead's "In Rainbows" is on track to make a No. 1 start on the first Official U.K. Albums chart of 2008.

The set, Radiohead's first release through XL Recordings, is likely to sell about 50,000 copies by the end of what is typically a slow week in the year, according to HMV, Britain's biggest music and entertainment retailer.

Expected to be trailing "In Rainbows" on the chart, to be published this Sunday, is Take That's "Beautiful World," followed by Leona Lewis' "Spirit" (Syco), Mika's "Life In Cartoon Motion" (Casablanca) and Michael Buble's "Call Me Irresponsible" (Reprise).

Radiohead, who recorded the 10-track set independently from their long-time label home EMI, provided one of the music industry's biggest talking points of 2007 when they initially released "In Rainbows" from their Web site in October solely as a download and allowed buyers to choose their own price for the recording.

London-based indie XL released the critically-lauded album on New Year's Eve in the world outside the United States and Japan, where the set is handled by ATO Records and Hostess Entertainment, respectively.

A No. 1 berth would come as something of a post-Christmas present for XL, which took something of a measured risk by signing up for a release which had already been in the public domain.

Speaking before the release date, XL founder Richard Russell told the release was "an experiment," both for the label and the band.

"Everything about this release is an experiment," he said. "Being (on) an independent label is another experiment for them."

On the Official U.K. Singles Chart, Leon Jackson, winner of the X Factor TV talent show, is expected to retain the top position with his cover of the Whitney Houston/Mariah Carey track, "When You Believe (Syco)," which was the U.K. Christmas No. 1 single.