New Spears' single tops US charts

Britney Spears has become only the second artist ever to have two singles to go straight into the US chart at number one.

Her new track 'Hold It Against Me' has topped the Billboard Hot 100.

Her 2009 single "3" also debuted at number one.

Mariah Carey is the only other artist to achieve the feat since the chart began 52 years ago.

'Hold It Against Me' is Britney's fourth career US chart topper.