American pop star Bruno Mars has fired Rihanna from the top of the charts with new single Grenade.
It is the second number one for the singer-songwriter who was acclaimed for his debut hit, Just the Way You Are, last year. The song is also in the top 20, holding onto the number 17 slot.
His chart success comes in the week he was nominated for the International Breakthrough Act in the Brit Awards and saw his new tour, Doo-Wops and Hooligans, sell out in record time.
Jessie J, winner of the BBC's Sound of 2011, saw her first single Do It Like a Dude climb the charts to claim the number two spot with Rihanna ft Drake settling for number three with What's My Name. Rihanna, however, can be consoled with holding onto the top of the album charts with Loud.
Katy B and Ms Dynamite's dance tune Lights On stayed at number four in the singles chart while X Factor winner Matt Cardle's previous number one When We Collide, a cover of Biffy Clyro's Many of Horror, slipped down to number five.
The highest new entry in the Top 40 was for the Glee cast with a cover of the Lady Gaga and Beyonce collaboration Telephone, which entered at number 25 - and also saw their version of Empire State of Mind join the charts at number 35.
Jay-Z and Kanye West have teamed up for meaty new single H.A.M, the second highest new entry at number 30.
Adele saw Make You Feel My Love, her Bob Dylan cover that became a favourite with X Factor auditionees, climb from 27 to number seven after it was featured in last week's ITV skating show Dancing on Ice.
Cee Lo Green, Rumer and Mumford & Sons take the third, fourth and fifth spots respectively in the album charts.
The highest new entry there comes from Emma's Imagination, the winner of Sky One's talent show Must Be the Music, whose album Stand Still is at number 14. Indie band British Sea Power enter at number 22 with Valhalla Dancehall while late Hawaiian ukulele player Israel Kamakawiwo'ole - Iz for short - is the third and final new entry in the album charts with Somewhere Over the Rainbow.