By Colin Paterson and Tim Masters
Entertainment reporters, BBC News
Lady Gaga's latest single Bad Romance is the current UK number one
MP3 players given as presents have helped boost UK single sales to an all-time high in the week after Christmas.
According to Official Charts Company figures, 4.22m singles were sold in the last week of 2009, beating the previous record of 4.03m over Christmas 2008.
And the Christmas chart battle between X Factor and Rage Against the Machine may also have had an effect.
"It has opened up people to downloading who may never have done before," said Music Week editor Paul Williams.
Lady Gaga was named on Sunday as last week's top-selling singles artist as Bad Romance returned to the number one spot. X Factor winner Joe McElderry's single The Climb went down to number two.
Williams told the BBC that the growth in the download market had changed the way that consumers behaved immediately after Christmas.
"It used to be on Christmas Day you'd have your lunch and maybe go for a brisk walk or settle down and watch the afternoon film," Williams said.
"Now, increasingly, people are going online to buy - particularly if they have got an MP3 player for Christmas and they want to feed their new gadget."
Download sites took advantage of the Rage Against The Machine chart battle
He added: "It used to be the case that the week after Christmas was pretty dead in terms of chart activity. Very few shops were open and people were really busy doing other things.
"But because there is this online element now - particularly with the singles chart which is almost exclusively download now - it has the opposite effect that people are buying more in the week after Christmas than they would ordinarily be."
Digital sales now account for around 98% of the singles market. The BPI, which represents UK record labels, has said it expects total single sales in 2009 to exceed 150 million.
The previous all-time record of 115.1 million was set in 2008. Final figures for 2009 will be published later this week.
Williams said that Joe McElderry's single bucked the download trend in that most were sold in a physical format. The Rage Against the Machine song was download only.
"We have in the market one particular outlet in iTunes that really dominates, but what happened with RATM was that other online players were cashing in - and therefore they were not only generating more business for themselves but increasing the size of the market overall."
But while the singles market is on record-breaking form, album sales have been in decline. According to Music Week last week's sales were 3.16 million - almost 12% lower than the same period last year.