Jessie J has knocked Flo Rida off the top of the charts with her single Domino.
The 23-year-old star sent the American rapper's track Good Feeling down to number two, the Official Charts Company said.
Brighton hip hop duo Rizzle Kicks went up two spots to number three with Mama Do The Hump, while Levels by Swedish DJ Avicii held on to number four.
American R&B artist Lloyd took fifth spot - up from 10 last week - with Dedication To My Ex (Miss That) featuring Andre 3000 and Lil Wayne.
The highest new entry in the singles chart was 15-year-old singer-songwriter Birdy's cover of indie folk band Bon Iver's track Skinny Love.
Meanwhile Bruno Mars leapfrogged Adele to take over at the top of the album chart with Doo-Wops And Hooligans.
Ed Sheeran's debut album release continued to slide, and now holds third spot. Indie rockers Maccabees were the only new entry to make the top 40, as Given To The Wild went straight in at four. Beyonce's album, 4, rose one place to five.
Jessie J, who achieved a second number one, paid tribute to her fans who downloaded the song before its release in shops.
"I want to say a massive thank you to all my fans, my Heartbeats, for buying Domino nine weeks before release. It's insane! I'm going to go and jump in a pool. I don't know where the pool is, but I'm going to find one!"
Domino is taken from her double-platinum debut album Who You Are, which has now spawned four top 10 hits.