Usher and Tameka Foster. (WENN/AFP)

Usher's bitter custody battle with his ex-wife Tameka Foster will resume on Aug. 13, despite the singer's request to postpone the hearing following his stepson's death last month.

Foster challenged her former husband's stall plea, insisting his call for sympathy was "bogus" - and the judge overseeing the case has agreed there's no need to hold up proceedings.

In court papers filed this week, Usher suggested the hearing would cause "unnecessary stress and strain" for himself and his ex.

But the case will continue in Fulton County court in Georgia as planned.

Usher is expected to return to the stand.

The couple was last in court in May when the Yeah! star was blindsided by questioning from his ex-wife's lawyer, who accused him of sleeping with another woman during a cross-examination about the reinstatement of a nanny.

During the three-day stand-off in the Fulton County courtroom, the hitmaker, who is fighting for more visitation, accused his ex of spitting on his girlfriend and throwing a plate of food at his car in a jealous rage. He also appeared to tear up when he was quizzed about his capabilities as a dad.

Foster and Usher divorced in 2009 after two years of marriage. They have two young sons.