Trump lawyer Chris Kise continued to spar with state attorney Louis Solomon during the testimony of Mazars General Counsel Bill Kelly.

After Solomon objected to a question posted in Kelly's cross-examination, Kise interjected to call out Solomon for being hypocritical about the bounds of acceptable testimony.

"Everything in this courtroom concerns me and my client, including your health," Kise said, referring back to his earlier concern about a courtroom COVID-19 outbreak.

"Thanks for your concern," Solomon responded offhandedly.

Trump and his attorneys have adjusted their seating compared to past days, possibly due to health concerns, so that Trump and Kise are sitting further from the state attorneys.

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's lawyers abruptly stopped the testimony of their first expert witness -- who was expected to testify for a full day or two -- after Judge Engoron limited the topic areas of his testimony.

Steven Witkoff, a real estate investor and longtime friend of Trump's, was brought into court by the defense team to testify that Trump's Doral golf club was undervalued in Trump's financial statements.

But Judge Engoron sustained an objection from the state barring any testimony about the valuation of Doral, significantly limiting Witkoff's testimony and appearing to hamper the defense strategy proposed by Trump's attorney Chris Kise.

Kise argued that the inaccuracies in Trump's statement of financial condition can cut both ways: Even if some properties were overvalued, other properties like Doral were significantly undervalued and balanced out the statement, according to Kise.

"It is highly, extraordinarily relevant if there are assets that are undervalued substantially on those same statements," Kise said. "They can't look at this one-sided."

State attorney Andrew Amer fiercely rebutted that argument, telling Engoron he should not take the defense's position that the inconsistencies "come out in the wash."

That argument appeared to convince Engoron, who said that overvaluations would not "insulate" a false valuation. He promised to sustain any objection that related to the value of Doral -- an approach Kise described as "lunacy."

"The reader of the financial statement has the right to know whether each particular number was accurate," Engoron said. "They are looking for accuracy."