Before today's first witness entered court, Trump attorney Chris Kise asked Judge Engoron to postpone today's proceedings after five members of the New York attorney general's team tested positive for COVID-19.

Describing the attorney general's conduct as "beyond irresponsible," Kise said that his team did not get adequate notice about the COVID exposures despite having close contact with positive individuals.

"Nothing else matters except for pursuing President Trump," Kise said. "We have the leading candidate for president of the United States in the courtroom today."

"The attorney general's office knew on Wednesday and didn't tell any of us," defense attorney Clifford Robert said. "We are truly in an outbreak."

Engoron declined to grant their requested delay.

In a statement, a spokesperson for New York Attorney General Letitia James said the state has complied with all CDC guidelines.

"Our office properly notified the court and defendants' counsel, and the court decided to proceed with trial today. If there were any concerns, defendants could wear masks today or at any point, but they have opted not to," the spokesperson said.

Trump called his former lawyer Michael Cohen a "proven liar" and "felon" as Trump entered the courtroom for his civil trial this morning.

"He's a felon, served a lot of time for lying, and we're just going to go in and see and I think you'll see that for yourself," Trump told reporters outside court.

Cohen pleaded guilty in 2018 to two separate criminal cases and eventually spent more than 13 months in prison -- but said that it was Trump who caused him to "follow a path of darkness."

-ABC News' Ricardo Montero contributed to this report.

Exiting his New York City apartment this morning, Michael Cohen told reporters he was "looking forward" to seeing Trump in court.

"It's been five years since we've been in the same room," Cohen said.

Cohen preemptively defended the credibility of his testimony and reiterated that he previously perjured himself "concert with and for the benefit of Donald J. Trump."

"My credibility should not be in question," Cohen said.

-ABC News' Eric Avram contributed to this report.

Donald Trump has arrived in court for the anticipated testimony of his former lawyer Michael Cohen.

New York Attorney General Letitia James is also attending the trial this morning.

James took her usual seat at the front of the courtroom's gallery, directly behind her team of lawyers at the counsel table.

The courtroom itself is nearly at capacity, with attendance matching the number of observers during the trial's opening statements.

Patrick Birney had been working for the Trump Organization for more than two years when a magazine article prompted him to change Trump's financial statement, the executive testified.

"There was an article written that stated that Mr. Trump's triplex was actually 10,900 or so square feet," Birney said, referring to a 2017 Forbes magazine article that alleged Trump had been lying about the size of his residence. (Judge Engoron decided in his partial summary judgment last month that the size was misrepresented.)

Birney, who was an assistant VP at the time, testified that Trump Organization executives, including former CFO Allen Weisselberg, "verified" the size and adjusted the next year's statement of financial condition. As a result, the penthouse was valued at $116 million in 2017 -- a steep drop from the 2016 valuation of $327 million.

Birney testified that he looked up comparable properties to come up with the value of the apartment going forward.

"I Google searched recent penthouse sales in Manhattan," Birney said, eventually landing on an web article about a penthouse purchased by billionaire Ken Griffin that set the record for most expensive home ever sold in the United States.

A price-per-square-foot for Trump's penthouse was determined based on that record-breaking sale, Birney said.

When Birney was tasked with finding comparable properties to value Trump's Mar-a-Lago Club, he similarly searched for nearby Palm Beach homes. However, Trump signed a deed in 2002 that limited Mar-a-Lago's purpose to a social club, the New York attorney general alleges, making the price of nearby residences irrelevant.

Asked if he was ever told about the deed by anyone at the Trump Organization, Birney replied, "I don't believe I was." Instead, he said he first learned about it during an "interview with the attorney general's office."

Court then adjourned for the day, with Birney's testimony scheduled to resume tomorrow morning.