Usher is being sued by his former nanny.

Cecilia Duncan - who was hired to look after the 'Yeah!' hitmaker's two sons, Usher V, five, and four-year-old Naviyd between December 2010 and September 2012 - has filed a lawsuit against the singer, alleging she was ''overworked'' and was not paid overtime, according to TMZ.

The ex-nanny claims she often worked over 40 hours a week, but wasn't being compensated for the extra hours and when she brought up her grievance to the 34-year-old star in 2011, he ignored her claims for more than a year and subsequently fired her last year.

Cecilia is thought to have filed a six-figure lawsuit against the 'Scream' singer for wrongful termination, failure to pay wages and is also seeking other unspecified damages.

However, Usher's camp denies any wrongdoing, branding the nanny's claims ''completely false'' and the lawsuit ''frivolous''.

The 'Climax' crooner was locked in a bitter custody battle with ex-wife Tameka Foster - the mother of his children - last year, with the judge eventually siding with the singer and awarding him primary custody of the couple's two sons.

Tameka attempted to request a retrial - citing that the judge in the case was biased after receiving campaign contributions from Usher's manager - but the appeal was denied.