The girl group's first single proper 'Wings' is currently outselling its nearest rival, Sam and The Womp's 'Bom Bom', by two copies to one.
Owl City and Carly Rae Jepsen vault up from 17 to three with 'Good Time', while Rita Ora's 'How We Do (Party)' slips to four.
X Factor contestant Lucy Spraggan is at five with her self-penned track 'Last Night'. The singer performed it on Saturday night's audition episode, but has since had to remove the song from iTunes.
N-Dubz rapper Fazer lands at 12 with his debut solo single 'Killer', Cover Drive are at 24 with 'Explode' and Cheryl Cole's 'Under The Sun' slips to 28.
Over on the album chart, Rita Ora is on course to claim her first UK number one record with ORA.
The London singer is hotly pursued by Elbow's Dead In The Boot B-sides collection at two and Of Monsters And Men's first studio album My Head Is An Animal at three.
Other new entries include Alanis Morissette's Havoc and Bright Lights at eight, Noisette's Contact at 27 and Slaughterhouse's Welcome To Our House at 30.
Watch the music video for Little Mix's 'Wings' below: