*Oprah Winfrey is set to spend two weeks in Philadelphia this month to testify in a defamation case linked to the sex-abuse scandal at her girls school in South Africa.

A federal judge this week refused to dismiss the suit filed by Winfrey’s ex-headmistress, paving the way for trial to begin on March 29, reports the Associated Press.

After the abuse complaints surfaced in 2007, Winfrey said she had “lost confidence” in headmistress Nomvuyo Mzamane and was “cleaning house from top to bottom.” A dormitory matron who worked under Mzamane was later charged in South Africa with abusing six students.

The judge found that Winfrey made both Mzamane and the dormitory parents appear “culpable” by telling parents, “I’m going to find a new head of the academy for the school. … Dorm parents are gone, (Mzamane) is gone.”

The statement suggests Mzamane had a role in the mistreatment of the students, “which clearly would tend to ‘blacken’ plaintiff’s reputation or injure her in her profession,” U.S. District Judge Eduardo Robreno wrote in a 128-page opinion issued Monday.

The talk show host, as a named defendant, must be in court and has rearranged her TV production schedule to do so, her lawyers said in a recent court filing. She also appears likely to be called as a witness.

Winfrey was in South Africa on Tuesday visiting the Oprah Winfrey Leadership Academy for Girls, near Johannesburg, according to her production company, Harpo. She opened the $40 million school for impoverished girls in January 2007 and recruited Mzamane, a Lesotho native, from a private school in Philadelphia.

Winfrey’s lawyers sought to dismiss the suit on grounds the remarks she made at an Oct. 20, 2007 meeting with parents and at a Nov. 5, 2007 press conference reflected only her opinions. But Robreno said a listener could infer she based the comments on facts gleaned from the school’s internal investigation.

Winfrey herself acknowledged the power of her words when she said in a deposition that she thought only two people — President Barack Obama and his wife Michelle — wield more influence in the media, Mzamane’s lawyers said in a brief.

“Oprah and Harpo await the opportunity to present the case in court,” her lawyer, Chip Babcock of Houston, said Tuesday in a statement issued through Harpo, which is also a named defendant.

In a brief filed Friday, Winfrey’s lawyers wrote that any damage Mzamane suffered was by her own conduct, “including presiding over a school where serious allegations of child abuse were made against the dorm parents.”

Winfrey’s lawyers tried to move the pending defamation trial to Chicago, where her show is based, but Robreno said it could be tried in Pennsylvania, where Mzamane lived when she filed suit in 2008 and where her reputation is perhaps most relevant. Mzamane is seeking more than $250,000.