The "blues-themed" new album that the Rolling Stones have been working on will reportedly feature a cameo appearance from Eric Clapton.

The news comes courtesy of the U.K.'s Sun tabloid, which quotes an unnamed source as saying Clapton (who can be heard with the Stones on an alternate version of "Brown Sugar" included on last year's Sticky Fingers reissue) bumped into the band because the two acts happened to be recording in the same London studio — and they ended up tracking a pair of songs under the guidance of producer Don Was.

"Eric was in the next studio along so he came in to say hello," said the source. "They ended up jamming and recorded two songs. Don reckons it’s the best thing he has ever done with the Stones."

As Stones fans are no doubt well aware, Was has been a member of the band's production stable for some time — he was behind the boards for 1994's Voodoo Lounge, 1997's Bridges to Babylon and 2005's A Bigger Bang. Even though many of the details of the new recording are still being kept under wraps, Keith Richards has said the sessions were among the most productive in the band's history and hinted that the results "might be a surprise to people." Ron Wood, meanwhile, added that the group "got on a blues streak" and cut covers of standards as well as new originals.

The Sun's sources also say the Stones so enjoyed getting back to work that they're already making plans for their next album — which they intend to start recording right away: "They have decided to go back in the studio later this month because they are enjoying it so much."

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