The People of the State of New York v. Donald J. Trump, et al, is scheduled to get underway in lower Manhattan at 10 a.m. with opening statements.

If opening statements are completed before the end of the day, the New York attorney general plans to begin her case by calling Trump's former Mazars USA accountant Donald Bender to the stand.

Mazars severed its business relationship with the former president last year after learning of the attorney general's findings during the AG's probe.

Though Trump has denied all wrongdoing alleged by the attorney general, Judge Arthur Engoron has already decided the central allegation against Trump and his co-defendants, ruling in a pretrial hearing last week that the AG had provided "conclusive evidence" that Trump overvalued his assets between $812 million and $2.2 billion.

The judge then canceled the Trump Organization's business certificates in New York, severely restricting Trump's ability to conduct business in the state moving forward -- a move that Trump attorney Alina Habba called "nonsensical" and "outrageously overreaching."

"In defendants' world: rent regulated apartments are worth the same as unregulated apartments; restricted land is worth the same as unrestricted land; restrictions can evaporate into thin air," Engoron wrote, citing multiple arguments made by defense to justify the allegedly inflated valuations of Trump's assets. "That is a fantasy world, not the real world."

Among the issues still to be determined at trial: What additional penalties Trump might face, and what might happen with the multiple causes of action included in the attorney general's suit.

Former President Donald Trump stepped up his attacks on the judge overseeing and deciding his case, writing on Truth Social overnight that Justice Arthur Engoron should resign and be sanctioned for "abuse of power."

Similar to an earlier post, Trump criticized allegations regarding the value of his Mar-a-Lago estate, in addition to an appellate court's ruling that his lawyers unsuccessfully tried to use to limit the timeframe of the case.

Former President Trump posted on his Truth Social platform Sunday night that he intends to attend the opening of the trial.

"See you in court -- Monday morning," he wrote in a post.

Earlier Sunday, multiple sources familiar with the decision told ABC News that Trump was expecting to attend.

Trump will have no speaking role in court on Monday, but it is anticipated that he'll return to the courthouse toward the end of the state's case when court records show he will be called as a witness.

Speaking outside the courthouse following his testimony for the defense, Donald Trump Jr. told ABC News that he seems to have a positive relationship with Judge Engoron.

"Perhaps there's a New York personality there, but no I think he understood," Trump Jr. said when ABC News suggested he and the judge appeared to get along. "I can't help myself even in this very serious situation. If you take yourself too seriously the world sort of sucks. You got to have a little bit of fun with it, so I did."

His relationship with the judge appears to stand in contrast to that of his father, who has accused Engoron of bias and insulted him from the witness stand.

"We had some quips in the courtroom the first time I was here," Trump Jr. said of Engoron. "Sort of gave me a fist bump on the way out. I guess I had a rather snappy response to something that was -- I can't even remember what it was right now. He said, 'That was really funny.'"

Asked by ABC News whether Trump Jr. shared his father's views about the judge being biased, the son demurred.

"Listen, I don't even know how far the gag order applies, so I don't need to do that and put myself -- I'm in enough crosshairs, guys," he said.