Prosecutors took care to emphasize at the start of former president Donald Trump’s Manhattan criminal trial last month that their credibility-challenged witness Michael Cohen’s testimony would be corroborated by evidence. The message: You don’t have to take his word for it.

But on some key aspects of the case, they’ve still been forced to rely on Cohen’s say-so. That made the cross-examination of Cohen this week the most high-stakes moment of the trial.

On Thursday, after extensive grilling of Cohen, Trump’s lawyers finally drew blood.

But how much did it undermine Cohen’s credibility - and potentially the prosecution itself?

Trump’s lawyer adamantly claimed he had caught Cohen in a lie from just days earlier. That’s not quite so clear, but there is no question that what transpired Thursday could cause jurors to second-guess key claims from Cohen, a witness they’ll be well aware has admitted to lying in proceedings before (on Trump’s behalf).

Given the importance of the exchange, it’s worth a parsing.

The focal point of the dispute is an 8:02 p.m. phone call on Oct. 24, 2016, during which Cohen discussed the Stormy Daniels hush money payment with Trump, he testified.

Prosecutors briefly broached the 8:02 p.m. call Monday during Cohen’s first day of testimony. Cohen said he had reached out to Trump’s bodyguard, Keith Schiller, “to discuss the Stormy Daniels matter and the resolution of it.”

The prosecutor asked whether the conversation included having “resolved that you were moving forward to fund the deal.”

Cohen replied: “Yes.”

But Trump’s lawyers suggested Thursday that this never happened. And they presented evidence that would suggest that the purpose of the call was entirely different.

Trump lawyer Todd Blanche noted that, shortly before the phone call, Cohen had been texting with Schiller about another matter: harassing phone calls he had been receiving, including from a phone whose user identified themselves as 14 years old.

Here’s the timeline:

• 7:48 p.m. Oct. 24: Cohen texts Schiller, “Who can I speak to regarding harassing calls to myself and office, the dope forgot to block his call on one of them.”

• 8:01 p.m.: Schiller leaves Cohen a voice mail.

• 8:02 p.m.: Schiller texts Cohen, “Call me.”

• 8:02 p.m.: Cohen calls Schiller. The call lasts 1 minute 36 seconds.

• 8:04 p.m.: Cohen texts Schiller the 14-year-old’s number.

• 7:58 a.m. Oct. 25: Cohen texts Schiller, asking if Schiller reached the family.

Blanche claimed these communications show Cohen lied about the phone call. He said Cohen had falsely testified to the purpose of the call, and he suggested that a phone call lasting 1 minute 36 seconds was too brief to have included talking to Schiller about both the harassment and the Daniels payment.

“That was a lie,” Blanche said twice.

Cohen stood by his testimony, but he also seemed to qualify it.

“Part of it was the 14-year-old, but I know that Keith was with Mr. Trump at the time, and there was more than potentially just this,” Cohen said. “That’s what I recall based upon the documents that I reviewed.”

Cohen said his comments about the hush money could have been as brief as “saying everything is being taken care of; it’s going to get resolved.”

Blanche challenged Cohen to admit that he hadn’t even spoken to Trump on the phone call.

Cohen responded: “No, sir, I can’t [admit that]. I am not certain that is accurate.”

“Based upon the records that I was able to review, in light of everything that was going on,” Cohen added, “I believe I also spoke to Mr. President Trump and told him everything regarding the Stormy Daniels matter was being worked on and it’s going to be resolved.”

Cohen went on to say that he hadn’t had his memory refreshed about the texts with Schiller - including by prosecutors - before Thursday’s testimony.

So what does it all mean?

The evidence does not prove that Cohen and Trump didn’t speak on the phone call or that they didn’t speak about Daniels. But Cohen had testified that he reached out to Schiller “because I needed to speak to Mr. Trump … to discuss the Stormy Daniels matter.”

At the very least, the new evidence suggests that the immediate impetus for the call was something different: the harassment Cohen was receiving. Neither prosecutors nor Cohen had broached that Monday, for whatever reason. And under cross-examination, Cohen seemed to allow that he was relying on a reconstruction of events - a reconstruction that, before Thursday, did not include the texts with Schiller.

Cohen’s testimony Thursday was also notably less firm. While he testified directly Monday to the purpose of the call being the Daniels payment and the payment having indeed been discussed, on Thursday he used phrases like “what I recall based upon the documents I received,” “I am not certain [Blanche’s characterization] is accurate,” “potentially” and “I believe.”

The importance of the Oct. 24 phone call is debatable. Prosecutors didn’t dwell on it or go into much detail, and it’s evident that Trump reimbursed Daniels for the hush money later.

But such a conversation, if it actually happened, would help prosecutors establish that Trump was included early on in the alleged conspiracy to cover up the payment.

And more than that, it could give jurors reason to doubt the testimony of someone they’ll probably already have viewed skeptically - and whose key claims, despite the insistence of prosecutors, simply can’t all be backed up by other evidence.