The X Factor Australia judge leads the tally for a fourth consecutive week, holding off competition from Birdy's 'Skinny Love', which holds at two.
Meanwhile, Flo Rida is the highest new entry after storming to three with 'I Cry', Taylor Swift slips four to five with 'We Are Never Ever Getting Back Together', and Florence + the Machine rebounds 13 to ten with 'Spectrum (Say My Name)'.
Further down the chart, Chiddy Bang jump 14 to 11 with 'Mind Your Manners', James Morrison leaps 18 to 13 with 'I Won't Let You Go', and Rita Ora's 'R.I.P' leaps 29 to 23.
Taio Cruz debuts at 28 with 'Fast Car', Cher Lloyd's 'Want U Back' re-enters at 36, and Jay Sean and Pitbull slip 32 to 38 with 'I'm All Yours'.
Outside the top 40, Sam and the Womp start at 46 with 'Bom Bom', and fun. re-enter at 50 with 'We Are Young'.
The Top 10 singles in full (click where possible for our reviews):
1. (1) Guy Sebastian ft. Lupe Fiasco: 'Battle Scars'
2. (2) Birdy: 'Skinny Love'
3. (*) Flo Rida: 'I Cry'
4. (3) Justice Crew: 'Boom Boom'
5. (4) Taylor Swift: 'We Are Never Ever Getting Back Together'
6. (6) Owl City ft. Carly Rae Jepsen: 'Good Time'
7. (5) Maroon 5: 'One More Night'
8. (7) The Script ft. will.i.am: 'Hall Of Fame'
9. (8) Far*East Movement ft. Cover Drive: 'Turn Up The Love'
10. (13) Florence + the Machine: 'Spectrum (Say My Name)'
Watch the music video for Guy Sebastian's 'Battle Scars' below: