Four of the biggest-selling bands in pop music are going head-to-head in the album charts.
Oasis album Stop The Clocks features Slide Away and Wonderwall
The Beatles, Oasis, U2 and Westlife are all releasing albums on the same day.
Oasis and U2 are releasing greatest hits albums Stop the Clocks and 18 Singles, alongside Westlife's The Love Album, and Love from The Beatles.
Take That comeback track Patience is also hitting shop shelves. It entered the charts at number four while still only available as a download.
HMV's Gennaro Castaldo said U2 - whose album features two new tracks - were likely to be the eventual victors in sales terms.
"Christmas starts here as far as music retailers are concerned, as it's not everyday that some of the world's biggest ever super groups have albums out.
"It's going to be close to see who comes out on top, but we reckon Oasis's Stop The Clocks will go to number one by the end of the week, though U2 may look to sell more copies of 18 Singles over the next month, or so."
Mr Castaldo added that it was possible that Take That could have more success in the singles chart this week.
Patience reached number four from download sales alone in this week's chart, beating former member Robbie Williams's single Lovelight, which rose to number eight.
Take That's new album Beautiful World will be out next Monday.