Usher has described his marriage to Tameka Foster as his "best mistake".

The 35-year-old singer opened up to the September issue of Oprah Winfrey's O magazine about his divorce from stylist Tameka - to whom he was married from 2007 to 2009.

When asked about his best mistakes, Usher replied: "Getting married at 28."

He continued: "Most people probably think I regret it because I ended up getting divorced, but it helped me learn that sometimes I think I know more than I actually do."

Usher was locked in a lengthy custody battle with Tameka, before he was made primary guardian of their two children, six-year-old Usher 'Cinco' Raymond V and five-year-old Naviyd Ely Raymond in 2012.

Asked about his best advice, the RnB star revealed how he had been given some important words of wisdom by music legend James Brown.

"'If you stay ready, you ain't gonna get ready.' James Brown told me that right before we performed together at the Grammys in 2005.

"I've never forgotten it, and I'm always telling people, 'Well, James Brown once told me...'."