Ariana Grande is way out in front to top the singles chart this weekend as online streaming counts towards sales data for the first time.
Us singer Ariana, 21, will also make her UK chart debut this weekend, with her single Problem featuring Iggy Azalea selling more than double her nearest rival Ella Henderson.
Chart bosses are including streaming from services such as Spotify and Deezer - alongside downloads and the small number of physical sales - from this week, with 100 streams of a song counting as one sale.
Figures from the Official Charts Company show Ariana's song has clocked up around 55,000 sales - including one per cent of those from streaming . Ella Henderson's song Ghost has 21,000 sales, eight per cent of which are from streaming.
Australian singer/songwriter Sia is expected to make it to number three with Chandelier.
Ed Sheeran's Sing - on course to be number four - is predicted to be the most streamed track of the week with 13 per cent of his sales accounted for through online listening, possibly given a boost by his appearance at Glastonbury at the weekend.
Other Glastonbury performers given a boost include Dolly Parton with her 1973 single Jolene on course to make the top 40.
The first official singles chart to include streaming will be announced on Sunday evening.