Britney Spears Network: Britney Spears' ex-manager asks judge to subpoena singer at defamation ...

PUBLISHED: 00:07 EST, 1 September 2012 | UPDATED: 01:09 EST, 1 September 2012

Ready to stand up in court? Britney Spears' former manager thinks if she can appear on The X Factor she can give evidence

Under conservatorship: Britney Spears' ex-manager argues her X Factor role shows she's able to give testimony

She is preparing to appear as a judge in front of millions in the revamped X Factor USA.

And now Britney Spears' former manager Sam Lutfi - who sued the star in 2009 claiming breach of contract and defamation - is trying to force the star testify at the upcoming hearing on the basis of her turn on the TV talent show.

Lutfi, who filed suit against Spears and her parents, James and Lynne Spears, is preparing to go to trail this autumn.

And since his former client is raking in $15million to star alongside Simon Cowell on the Fox show, the talent manager claims she is competent enough to testify in court, according to TMZ.

Lutfi filed papers at Los Angeles County Superior Court on Thursday, asking a judge to request Britney's conservators make her available as a witness, the website reports.

He is believed to want to see the Toxic singer grilled about alleged defamatory statements her parents made about him, including claims he drugged her and cut her phone wires to keep her away from her family.

He is also believed to want the 30-year-old star questioned about an alleged management contract guaranteeing him a slice of her fortune.

According to the filing, Spears' conservators argued she is not mentally competent enough to testify as a witness.

Lutfi is said to have included a DVD of Britney on the show in order to prove that's not the case, arguing the footage shows Spears is both articulate and competent, and should thus be capable of giving testimony.

Old acquaintance: The singer was involved with Lufti in 2008

Old acquaintance: Spears was sued in 2009 by her former manager Sam Lutfi, left with the singer in 2008. Lutfi claimed breach of contract and defamation

A hearing is scheduled for September 25, and a judge has yet to rule on the request.

Lutfi's filings mark the latest skirmish in a legal battle that has been going on between Spears and her former manager for years.

In April, her conservators filed legal papers demanding Lutfi hand over $121,000 in fees for work done obtaining a restraining order against him.

The sum had already been awarded, but a payout was put on hold until his appeal against the decision was heard.

If she can star on X Factor... Britney Spears' former manager Sam Lufti wants to force her to testify in court

Ready to stand up in court? Spears next month will star on TV talent show X Factor, appearing alongside (L-R) L.A. Reid, Demi Lovato and Simon Cowell

Court documents stated: 'Although the requested fees and costs may be greater than is typically associated with the grant of restraining orders, this was a complex and highly contested matter.'

In July a judge ordered Lutfi pay the entertainer's estate $92,845 in attorneys' fees.

Spears' sizable assets were placed under the control of a conservatorship managed by her father and her lawyer,Â following her mental meltdown and subsequent sectioning in 2008.

Due to her mental health issues, it was necessary for her to get approval from the court to join the hit talent show, set to premiere with Spears on the judging panel alongside L.A. Reid, Demi Lovato and Simon Cowell on September 12.