WASHINGTON — Roger Clemens told Yankees teammate Andy Pettitte nearly 10 years ago that he used human growth hormone, Pettitte said in a sworn affidavit to Congress, The Associated Press learned today.

Pettitte disclosed the conversation to the congressional committee holding Wednesday's hearing on drug use in baseball, a person familiar with the affidavit said. The person spoke to the AP on condition of anonymity because the document had not been made public.

According to the person familiar with the affidavit, who said it was signed Friday night, Pettitte also said Clemens backtracked when the subject of HGH came up again in conversation in 2005, before the same House committee held the first hearing on steroids in baseball.

Pettitte said in the affidavit that he asked Clemens in 2005 what he would do if asked about performance-enhancing substances, given his admission years earlier. According to the account told to the AP, the affidavit said Clemens responded by saying Pettitte misunderstood the previous exchange in 1999 or 2000 and that, in fact, Clemens had been talking about HGH use by his wife in the original conversation.

"We don't know what Andy said," Clemens' lead lawyer, Rusty Hardin, said in a statement e-mailed to the AP by his spokesman. "We look forward to hearing tomorrow."

The existence of the affidavit first was reported by The New York Times. The details of its contents were first reported by the AP.

The news came on the eve of Clemens' much-anticipated appearance to testify before the House Committee on Oversight and Government Reform. His former personal trainer, Brian McNamee, is Wednesday's other main witness. McNamee told baseball investigator George Mitchell that he injected Clemens with steroids and HGH at least 16 times from 1998 to 2001. Clemens repeatedly has denied those allegations, including, he said, under oath in a deposition last week.

Pettitte also sat for a deposition at the beginning of last week, and had been scheduled to testify at the hearing. But he asked the committee to allow him to give an affidavit instead of appearing at the hearing, the person familiar with the document said. Pettitte was dropped from the witness list Monday.

McNamee also accused Pettitte of using HGH, and after the Mitchell Report's release in December, Pettitte acknowledged that he did.

On Tuesday, Clemens made the rounds on Capitol Hill one last time, wearing a gray pinstriped suit and squeezing face-to-face meetings into the busy schedules of committee members. He met with five lawmakers over a four-hour span Tuesday, on top of the 19 he saw Thursday and Friday.

"I enjoyed talking with him," said Rep. Diane Watson, D-Calif., who said the discussion included baseball stories and personal accounts about the Sept. 11 attacks. "It's always good to meet the person who is in the spotlight. ... I told him, 'This is not a trial."'

But it might very well feel like one when Clemens and McNamee sit at the witness table and — under oath — offer what will surely be contradictory versions as to whether Clemens used steroids and HGH.

"I couldn't tell you who's telling the truth," Watson said.

Before Pettitte's affidavit came to light, Clemens got some help in his public relations push from a different ex-teammate Tuesday.

"I have never had a conversation with Clemens in which he expressed any interest in using steroids or human growth hormone," Jose Canseco said in a sworn affidavit, dated Jan. 22, that was submitted to the committee. "Clemens has never asked me to give him steroids or human growth hormone, and I have never seen Clemens use, possess or ask for steroids or human growth hormone."

In his affidavit, Canseco disputes various statements of McNamee's in the Mitchell Report. The affidavit also says "neither Senator Mitchell nor anyone working with him" contacted Canseco to attempt to corroborate things McNamee said.

Canseco's book about steroids in baseball, "Juiced," drew Congress' attention in 2005, leading to that year's hearing.

The anticipation of Wednesday's hearing rivals — if not surpasses — that of the hubbub before March 17, 2005, when Mark McGwire, Sammy Sosa and Rafael Palmeiro testified before the same committee in the same wood-paneled House hearing room. McGwire avoided answering questions about steroid use that day by repeatedly saying "I'm not here to talk about the past" — and his reputation has shown no signs of recovery.

"I think Roger's fully prepared to testify fully and truthfully," Hardin said. "He IS here to talk about the past."

McNamee has kept a low profile in the buildup to the hearing. He gave a closed-door deposition under oath last week, two days after Clemens did, and has been waiting until the hearing itself to retell his story.

Clemens didn't have much to say Tuesday as he walked the hallways from appointment to appointment. He said he was getting a chance to meet some "interesting people," and he waved appreciatively when two bystanders yelled: "We love you, Rocket!"

In a late addition to its case, Clemens' camp planned to submit to the committee on Wednesday a letter from a Baylor College of Medicine professor who examined medical records supplied by Hardin's office. The physician, Dr. Bert O'Malley, wrote that the records, which covered Clemens' time with four baseball clubs from April 1995 to August 2007, were "devoid of suspicious indications" of steroid use.

Although some congressmen have emphasized the hearing is not solely about Clemens or even baseball — concern about steroids and substance abuse among young people is the oft-stated mission — the focus on the 45-year-old pitcher became more apparent after several other witnesses were scratched. Like Pettitte, former Clemens teammate Chuck Knoblauch and convicted steroids distributor Kirk Radomski were dropped Monday.

The only scheduled witness besides Clemens and McNamee is Charles Scheeler, a lawyer who helped produce the Mitchell Report.

AP Sports Writer Joseph White contributed to this report.