Little Mix could be in line for their first number one album, days after the release of Glory Days.
The collection, which hit the shelves on Friday, is the band's fourth studio album in as many years - following their rise to fame after winning The X Factor in 2011.
While making the top five in the official charts, previous albums DNA (2012), Salute (2013) and last year's Get Weird, fell short of the top spot.
After selling more than 64,000 copies halfway through its first week, Glory Days is set to become one of the fastest -selling albums of the year.
But it still faces competition from heavy metal band Metallica's 10th studio album Hardwired...to Self-Destruct.
A win for the American rockers, formed in 1981, would be their first number one since Death Magnet in 2008.
Meanwhile, Bruno Mars's 24K Magic is set to join the top five at number three, while Michael Ball and Alfie Boe's Together and Elvis Presley's The Wonder Of You, take fourth and fifth place.
In the singles charts, Clean Bandit are on their way to a third week on top with Rockabye, but could still face tough competition from Rae Sremmurd's Black Beatles, featuring Gucci Mane.
Coming in third so far is Little Mix again with Shout Out To My Ex, followed by James Arthur's Say You Won't Let Go and Bruno's 24K Magic track.
Don't Wanna Know, by Maroon 5, looks set for a new peak position at number six, while Craig David's Children in Need single All We Needed - from his former number one album Following My Intuition, has jumped to 14 following the BBC's special charity programme on Friday.