Janet Jackson made a surprise appearance in a Los Angeles courtroom Tuesday for a trial pitting her mother against AEG Live, the promoter of her late brother’s doomed comeback tour.

The pop star wore a black trench coat, dark pants and her tawny curls were tied back in a loose ponytail as she sat in the front row next to family matriarch Katherine Jackson.

The Grammy winner, recently declared a “billion dollar entertainer” by Variety, is on the witness list for the lengthy civil trial in the family’s bid to show that AEG Live was negligent in overseeing Michael Jackson’s preparation for the “This is It” tour.

But the “Control” singer was not scheduled to take the stand Tuesday and instead appeared to see AEG honcho Paul Gongaware be called to testify, Katherine Jackson’s lawyer said.

“She wants to hear Gongaware’s excuses,” lawyer Brian Panish said.

The Jackson family contends that the Gloved One was readying for the tour under the care of Conrad Murray, the disgraced physician who is now imprisoned for supplying Michael with the surgery strength anesthetic on which he overdosed in June 2009, shortly before “This is It” was due to kickoff.

Janet first entered the courtroom alongside her older sister Rebbie, and it was Rebbie who exited the room when AEG’s lawyer objected to two family members who are on the witness list being permitted to sit in the gallery.

The judge had earlier agreed Katherine only needed one relative to be at her side to provide support.

As Janet left court for lunch amid tight security, she waved to fans and was flanked by Katherine, Rebbie and brother Randy.

Earlier in the day, Gongaware testified that he was a logistics manager on Michael’s “Dangerous” tour in 1993 but never knew about the King of Pop’s addiction to pain meds until the iconic entertainer publicly announced his need for rehab.

Gongaware said he knew of “two occasions” when Michael used painkillers between shows, but he claimed he didn’t grasp the scope of the singer’s sickness until the taped 1993 announcement.

“I would dispute knowing that he had a problem,” Gongaware said. “I wasn’t aware that there were problems.”

JOE KLAMAR/AFP/Getty Images

Randy (l.) and Rebbi Jackson, brother and sister of the late Michael Jackson, previously attended a court hearing on April 29.

Gongaware, the company’s co-Chief Executive Officer, was grilled about internal AEG emails that discussed planning for the “This Is It” shows in London.

One message sent from Gongaware to co-CEO Randy Phillips on Feb. 27, 2009 referred to the “Thriller” singer as “Mikey” and urged for him to be shown tough love ahead of a critical press conference announcing the comeback gigs.

“We cannot be forced into stopping this, which MJ will try to do because he is lazy and constantly changes his mind to fit his immediate wants,” read the email projected on a screen for jurors.

Gongaware said his use of “Mikey” was affectionate, not disparaging, and that the “lazy” crack amounted to a “poor choice of words” but one that accurately reflected how Michael “really didn’t like to rehearse” or “do these kinds of things.”

He also defended a March 2009 email that instructed his assistant to adjust the color-coding of a tour schedule so Michael’s workload would appear less rigorous when the singer saw it.

“Figure it out so it looks like he’s not working so much,” Gongaware told the assistant.

Panish, the Jackson family’s lawyer, asked if Gongaware was trying to “fool” Michael into thinking his schedule was easier than it in fact was.

“I wasn’t trying to fool him,” Gongaware replied. “I was trying to present it in the best possible light.”

Katherine Jackson’s effort to argue negligence on AEG’s part depends on proving that the concert promoter failed to properly investigate and supervise Murray, who was convicted in 2011 of involuntary manslaughter in her son’s death.

AEG has denied any wrongdoing, arguing that Michael personally hired Murray and kept his use of the surgery strength anesthetic propofol a fiercely guarded secret.

Gongaware briefly addressed the topic of Dr. Murray in his testimony Tuesday by saying he believed AEG had no choice but to work with the Vegas cardiologist.

“In this case, Dr. Murray was recommended by the artist. In fact, the artist insisted,” he said.

ndillon@nydailynews.com