The singer is trailed by The Saturdays' latest cut '30 Days', which is the midweek chart's highest new entry at number two and is just a few thousand copies behind.
Carly Rae Jepsen's 'Call Me Maybe' is at three, fun.'s 'We Are Young' is at four and Alex Clare's 'Too Close' rounds off the Top Five.
D'banj lands at number nine with 'Oliver Twist', Scissor Sisters are at 10 with 'Only The Horses' and Skepta's 'Make Peace Not War' is currently at 23.
Further down the chart, Ben Howard is at 38 with 'Only Love' and Skrillex is at 39 with 'Bangarang'.
Over on the album chart, Tenacious D are on course to claim their first UK number one album with Rize of the Fenix.
The Jack Black and Kyle Gass duo have pushed former number one Strangeland by Keane down to two, while Ren Harvieu is at three with Through The Night.
Garbage enter at number five with Not You Kind Of People, Glee's The Graduation Album is at 15 and Gossip are at 35 with A Joyful Noise.
Watch the music video for Rita Ora's 'R.I.P.' below: