Rihanna is due to appear in court in Los Angeles later in the assault case of her former boyfriend Chris Brown.

The 21-year-old singer is expected to testify as a witness against Brown, who is accused of assaulting her during an altercation in February.

Brown has pleaded not guilty to charges of assault and making criminal threats. He faces five years if found guilty.

Rihanna was subpoenaed to appear in court earlier this month, but it is not guaranteed that prosecutors will use her as a witness.

However, the singer's lawyer told the New York Daily News that he “fully” expected Rihanna to be asked to testify.

He added: "She will testify truthfully.”

Brown has been accused of hitting Rihanna during the row outside a parked car in Los Angeles in February.

The incident forced both stars to miss the Grammy Awards.

Rihanna and Chris Brown