AceShowbiz - American R&B stars Rihanna and Bruno Mars are holding their own atop the U.K. music charts . Her album "Loud" and his single "Grenade" are at number one.

Rihanna managed to beat off competition from rapper/singer Plan B, whose "The Defamation of Strickland Banks" returned to the charts at number two. Cee-Lo Green's "The Lady Killer" was at three while Rumer's "Seasons of My Soul" and "Mumford & Sons' Sigh No More" followed at four and five respectively.

Mars ruled the singles chart with his hit "Grenade", followed by newcomer Jessie J's "Do It Like a Dude" at two. Rihanna's single "What's My Name?" sat pretty at three, while Katy B's "Lights On" came in at four and Matt Cardle's "When We Collide" rounded out the top five.