The government lawyers prosecuting former baseball star Roger Clemens should not have been surprised by Andy Pettitte’s admission Wednesday that he may have misheard his former teammate and friend tell him that he’d used performance-enhancing drugs, according to former federal prosecutors.

In preparation for taking the witness stand, former prosecutors said the government team likely would have asked Pettitte how sure he was of his recollection of the conversation with Clemens during a workout at the pitcher’s home gym in 1999 or 2000.

View Photo Gallery: Once destined for the Hall of Fame, one of Major League Baseball’s brightest stars — and its most decorated pitcher — became the central figure in the game’s sordid steroids drama. A judge has declared a mistrial in his perjury trial. Clemens is on trial for a second time, charged with lying to Congress about using performance-enhancing drugs. 

Until Wednesday, Pettitte generally had not wavered from his assertion that Clemens confided in him about his use of HGH. He repeated that testimony Tuesday, which was critical to the government’s case that Clemens lied to Congress in 2008 when he denied using the banned substances.

But Pettitte had earlier expressed some doubt about his memory of the conversation to congressional investigators.

“Roger told me that he didn’t take it, and I misunderstood him. I took it for that, that I misunderstood him” in 1999 or 2000, he told them in 2008.

Defense lawyer Michael Attanasio apparently saw an opening, and pressed Pettitte on it Wednesday.

That prosecutors from the District’s U.S. Attorney’s Office did not specifically revisit Pettitte’s conflicting account under cross-examination Wednesday when they had a chance suggests that they didn’t want to dig a deeper hole, some attorneys say.

“They didn’t want to go there for fear of getting worse answers,” said Andrew White, a former federal prosecutor, “For fear that Pettitte isn’t going to go out of his way to harm his friend.”

Former federal prosecutors agreed that Pettitte’s pullback was a big boost to the defense team, but varied in their assessments of how much of a problem that testimony would be for the government.

Prosecutors are laying the groundwork for the testimony of former strength coach Brian McNamee, who is expected to testify that he injected Clemens with steroids and HGH on several occasions.

Michael Volkov, another former federal prosecutor, cautioned that Pettitte’s uncertainty is “not devastating.”

The case, he said, still hinges on what the jury thinks of McNamee and whether his story is backed up by the evidence, including needles that prosecutors have said contains Clemens’s DNA and traces of performance-enhancing drugs.

On the other hand, White said that Pettitte’s admission adds credibility to Clemens’s reaction to a separate conversation in 2005. At a time when performance-enhancing drugs were in the news, Pettitte asked Clemens how he would handle media questions about his use of steroids. Pettitte said Clemens responded, “What are you talking about?”

“This sets up a major league positive scenario for the defense,” White said, “and a possible basis for the misunderstanding that Pettitte now acknowledges he might have had.”

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