Music mogul Simon Cowell has expressed surprise at the speed of Leona Lewis's rise to fame in the US.
Lewis's single Bleeding Love currently tops the Billboard Hot 100 Chart, making her the first British female artist to achieve the feat in over 20 years.
"To say this has happened quickly is the understatement of the year," Cowell said.
"We were getting calls saying: 'This record is on fire', and: 'It's going to chart high'. Then we got one saying: 'It's gone in at No.1'. Nobody expected that.
"The amazing thing is I would say that 98 per cent of people in America still don't know who Leona Lewis is."
Cowell recently appeared alongside Lewis on the Oprah Winfrey show, a move that is believed to have helped the single's success.
He also helped negotiate the X-Factor winner a £5 million US contract.
Kim Wilde was the last British female to top the US singles chart with her 1987 cover of You Keep Me Hangin' On.