Operatic vocal group Il Divo and Kate Bush's first album in 12 years are both vying for the top slot in the charts this weekend.
Il Divo were formed in 2004 by X Factor judge Simon Cowell
Music retailer HMV says Il Divo's CD Ancora is out selling Bush's album Aerial in its stores.
But at Virgin Megastores a spokesman said Bush's album was in the lead, beating the "popera" group four to one.
Westlife is currently top of the album chart with Face to Face, which edged out Robbie Williams at the weekend.
Il Divo were formed in 2004 by X Factor judge Simon Cowell.
"It's not surprising that their new album looks set to get off to a chart-topping start," said HMV's head of music Phil Penman.
"Despite 'crossing-over' from a classical background, I suspect they'll be taking on the likes of Eminem, Madonna and Robbie to be the biggest-selling artists of the Christmas period."
But at Virgin Megastores a spokesman told the BBC News website: "Kate Bush is outselling Il Divo four to one. It is definitely going to be one of those two at number one this week.
Bush, pictured here in 1979, had not released a record since 1993
"We predicted Kate Bush would be number one, we were fairly confident from the start. We do sometimes have varying sales from HMV depending on clientete."
A year ago the operatic quartet knocked Robbie Williams from the top of the album chart with their self-titled debut album.
Aerial is Kate Bush's first album since the release of The Red Shoes, which reached a UK chart peak of number two in November 1993.
Her latest album received a mixture of rave reviews and qualified praise from the national press.
Despite "a massive day one rush" on Monday, HMV did not expect Bush's album sales to exceed those of Il Divo.
Nevertheless Mr Penman said: "I can see this album becoming yet another classic, which, despite being a double-CD, will sell consistently well in the coming weeks."