Jessie J has scored her third UK number one single, as a US singer became the first act to enter the top 40 based on streaming alone.
The R&B star from London shot straight to the top spot with Bang Bang, her collaboration with rap superstar Nicki Minaj and Ariana Grande.
The single achieved 92,000 downloads and was streamed more than 800,000 times to give an overall tally of almost 100,000 chart sales, the Official Charts Company said.
Bang Bang, which knocked Sigma and Paloma Faith's Changing off the top spot, is Jessie J's first single from her album Sweet Talker and her first chart-topper since Domino in January 2012.
She said: "To be number one for in the UK for the first time in three years... I'm going to celebrate every minute of it, I might even go bowling?!"
The track also gives rapper Minaj her first UK number one single while US star Grande returns to the top of the chart after her song Problem reached the summit in July.
Meanwhile, American singer/songwriter Meghan Trainor became the first artist to chart to reach the Top 40 based on streams alone.
All About That Bass climbed 20 places to number 33 this week ahead of its official release, after racking up 1.17 million streams across audio streaming services including Spotify, Deezer and Napster.
It was announced in June that songs played on streaming services would count towards the UK's singles chart after m usic streaming doubled in popularity in the UK between 2013 and 2014, from 100 million to 200 million streams a week.
Martin Talbot, chief executive of the Official Charts Company, said: "Congratulations to Meghan Trainor, who scores an historic first in the Official Singles Chart with her single All About That Bass.
"In scoring the first Top 40 hit on streams alone, she really has broken new ground."
Cilla Black just missed out on the Top 40 after her single Anyone Who Had A Heart finished at number 47.
The song had re-entered the midweek chart at number 40 following the success of Sheridan Smith's ITV biopic Cilla.
In the album chart, British indie band Alt-J hit the top spot with This Is All Yours, the follow- up to the band's Mercury Music Prize-winning debut, An Awesome Wave.
Vocalist and keyboard player Gus Unger-Hamilton said: "We're over the moon to see our album at number one.
"It was never something we thought we'd achieve, but it's our fans who have put us there, so we owe this to them."