Adele album on course for UK chart history
Adele's album could be the UK's fastest-selling album ever, having already sold more than half a million copies in just three days.
The total sales for 25 stand at 538,000 so far, with four days of the chart week still to run.
Only two albums have sold more than 500,000 copies in a week.
Take That's Progress sold 519,000 in its debut week in 2010, and Oasis's Be Here Now, the current record holder, sold 696,000 in its first week in 1997.
Meanwhile in the US, Adele has sold a record-breaking 2.3 million copies of the album so far.
The sales figures mean the record is on course to break the record currently held by boy band NSync's 2000 album No Strings Attached, which sold 2.4 million copies in its first week of release.
Adele performed her hit single Hello on Saturday Night Live at the weekend. That track alone has sold 2.5 million copies in the four weeks since it has been on sale.
Elsewhere in the UK chart, Elvis's former number one collection If I Can Dream is back at number two on the mid-week album chart, and Justin Bieber's Purpose is at three.
Enya's first album in seven years, Dark Sky Island, is currently at number four and last week's number one, One Direction's Made in the A.M., is at five.
There are a further nine new entries heading for this week's top 40 album chart.
They include a special edition of Take That's III, Olly Murs with Never Been Better, Cilla Black's The Very Best of and Tracey Chapman's Greatest Hits.
On the singles mid-week chart, Justin Bieber and Adele are battling it out, with Bieber's Sorry ahead of Adele's Hello by 3,000 copies.
Bieber's Love Yourself remains at three and his What Do You Mean is at number five mid-week.
His three entries in the Top Five last week made him the first male artist to achieve that feat in 34 years, since John Lennon in January 1981.