During a second day of testimony in the perjury trial against All-Star pitcher Roger Clemens, his old teammate Andy Pettitte walked back some of his previous testimony.

Yesterday, Pettitte said that he remembered having a conversation with Clemens in 1999 or 2000 in which Clemens admitted to using human growth hormone.

"Roger had mentioned to me that he had taken HGH," Pettitte testified according to The Los Angeles Times. "And that it could help with recovery, and that's really all I remember about the conversation."

But today, facing cross examination, Pettitte tempered some of his testimony. USA Today reports:

"In Pettitte's second day of testimony at Clemens' federal perjury trial, he was asked by defense attorney Michael Attanasio if he thought it was fair to say it was '50-50 you might have misunderstood.'"Pettitte replied: 'I'd say that's fair.'"Pettitte's admission would seem to help establish reasonable doubt about whether Clemens lied before Congress when he said in 2008 that he never used steroids or HGH."

The AP reports that Clemens' lawyers asked the judge in the trial to strike Pettitte's testimony because it was "insufficiently definitive."

The AP adds that this testimony should not come as a surprise to prosecutors, because Pettitte gave similar testimony in a 2008 deposition. In that deposition, Pettitte said that in 2005, after he asked Clemens what he would say if reporters asked him about using HGH, Clemens told him that he had "misunderstood him," that he was talking about his wife's use of HGH.

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