The 18-year-old Canadian singer's first UK release currently leads the tally, 5000 copies ahead of David Guetta and Sia's 'Titanium' at two, the Official Charts Company reports.
Meanwhile, last week's chart toppers Cover Drive dip to number four with 'Twilight', Gotye's 'Somebody That I Used To Know' advances from seven to six, and Pitbull and Chris Brown's 'International Love' rises from nine to eight.
Further down the chart, Lana Del Rey lifts from 14 to 11 with 'Born To Die', Pixie Lott's 'Kiss The Stars' leaps from 19 to 13, and Ed Sheeran's 'Drunk' vaults 29 to 17.
Feeder's 'Borders' debuts at 35, and Cher Lloyd's 'Want U Back' is at 37.
On the albums chart, Lana Del Rey leads the tally with her debut LP Born To Die, which is outselling the second-highest new entry - Leonard Cohen's Old Ideas - by two to one.
Meanwhile, Ed Sheeran's + is at three, Jessie J's Who You Are climbs from seven to six, and Christina Perri jumps from 37 to ten with Lovestrong.
Sunday's official chart is announced on Radio 1 between 4pm and 7pm.
Watch the music video for Alyssa Reid's 'Alone Again' below: