Prosecutors and defense attorneys began debating the ground rules Wednesday for testimony from two critical witnesses in the perjury trial of former standout pitcher Roger Clemens.

Clemens’s defense team is trying to block government lawyers from telling jurors that Andy Pettitte, Clemens’s former teammate and workout partner, was injected with performance-enhancing drugs by former New York Yankees trainer Brian McNamee.

In court filings, defense lawyers say they want to “avoid guilt by association” and are concerned that jurors will assume that Clemens was also supplied by McNamee because the two former teammates shared a trainer.

Federal prosecutors argued that how Pettitte came to use steroids was relevant to the case. “You simply cannot strip out half the narrative,” Assistant U.S. Attorney Steven Durham told U.S. District Judge Reggie Walton,

The debate came as jury selection continued in Clemens’s second trial on charges that he lied to Congress when he denied using performance-enhancing drugs. The first trial ended last summer after just two days following a basic error by government lawyers.

Pettitte, who recently re-joined the New York Yankees out of retirement, has admitted taking human growth hormone. Pettitte told a House panel investigating steroids in professional baseball that Clemens had admitted to him that he had taken the same drug.

In a preview of the defense team’s thinking, Clemens’s attorney said they would take the position that Pettitte misunderstood Clemens.

“A simple misunderstanding,” said lawyer Michael Attanasio. “A comment made in passing in the middle of an intense workout.”

Jury selection is expected to continue through Monday with lawyers narrowing the pool of potential jurors to 12, plus four alternates.

The lineup of potential jurors Tuesday included far more Clemens fans than in previous days, prompting government lawyers to ask whether they could set aside their favorable views of baseball’s most-decorated pitcher.

One man called Clemens “a great baseball player.”

Another went further, referring to him as “the greatest pitcher of all times.”

Durham responded, “I’m not going to quarrel with you on this.” But he pressed whether the prospective juror could ignore Clemens’s star power in this case and instead judge him like anyone else.

Walton challenged another possible juror who expressed reservations about serving because of religious objections to judging others.

“Who is supposed to do it while we’re here on earth?” Walton asked, before dismissing the juror.

This item has been updated.

Read more: Clemens trial coverage