While testifying today at the trial of his longtime teammate and friend Roger Clemens at the federal court in Washington D.C., the New York Yankees' Andy Pettitte spoke about his admiration for the former pitcher, their workouts with trainer Brian McNamee, and his admitted use of performance enhancing drugs.

Facing Clemens from the witness stand, Pettitte testified that both of the players valued McNamee's skills and the intense training sessions they had with him while they pitched for the Yankees. Although he had not spoken with Clemens for some time because of the criminal trial, Pettitte said he still considered him a friend.

Clemens was indicted in August 2010 on charges of obstruction of Congress, perjury, and false statements as a result of testimony he gave to Congress regarding use of performance enhancing drugs, specifically steroids and human growth hormone, or HGH.

Clemens was charged with making the false statements to congressional investigators in a deposition on February 5, 2008. The perjury charges arose from his February 13, 2008 testimony before the House Oversight and Government Reform Committee. Last year Judge Reggie Walton declared a mistrial after the prosecutors referenced evidence that the judge had prohibited from being introduced to the jury.

McNamee has told federal investigators and Congress that he injected Clemens with steroids and growth hormone in 1998, 2000 and 2001.

Pettitte testified that in either 1999 or 2000 while working out with Clemens at his home Clemens told him that he used HGH.

"Roger had mentioned to me that he had taken HGH, and that it could help with recovery, and that's really all I remember," Pettitte testified before the jury.

Pettitte's testimony is expected to be a key part of the prosecution's case. In opening statements Clemens defense team told the jury that Pettitte had misremembered conversations he and Clemens had about the use of HGH.

Testifying Tuesday Pettitte said that initially he did not know about HGH at the time, but said he became interested in it and decided to use it when he was injured during the 2002 baseball season.

"Someone else injected me," Pettitte testified when he was asked how he took the drug by prosecutor Steve Durham.

Pettitte testified that he took it twice over a two day period. Asked by prosecutor Steve Durham if it helped Pettitte overcome his injuries Pettitte testified, "I don't think so."

Pettitte told the jury that in 2004 after becoming injured in his first game that he again took HGH to help him recover from a torn tendon and testified that he injected himself with the substance.

Asked why he took the HGH, Pettitte told the jury, "I guess just out of desperation."

In testimony that will be key for Clemens defense Pettitte testified that as congressional hearings loomed about performance enhancing drugs in professional sports, Clemens told him he never used HGH, but his wife did. While the two were attending spring training while with the Houston Astros, Pettitte said he asked Roger what he would say when asked about using performance enhancing drugs.

"I knew I was very approachable by the media … I was concerned with what I would say if asked by the media," Pettitte told the court about why he was asking Clemens about HGH.

"He said what you are talking about. I didn't tell you that … he said I told you my wife Debbie used it," Pettitte told the jury, recalling what Clemens told him.

"I was a little flustered," Pettitte testified.

Under questioning from the prosecutors Pettitte told the jury he felt bad about his use of HGH.

"I don't want kids to think it's OK … if I hadn't done it, I wouldn't be here today," Pettitte said.

Clemens' defense attorney Michael Attanasio focused on Clemens' intense work ethic and his stellar career as a pitcher, which lead him to seven Cy Young awards.

Asking about Clemens records and power as a pitcher Attanasio asked, "Did it have anything to do with HGH or Steroids?"

"No," Pettitte told the court.

Pettitte appeared uncomfortable at times, rubbing his head and face when prosecutors and Clemens defense team had sidebar discussions with Judge Reggie Walton.

Pettitte's testimony resumes tomorrow morning at 9:00am.