Andy Pettitte was removed from the witness list for Wednesday's hearing. ((Tony Dejak/Associated Press))

Roger Clemens and his accuser, Brian McNamee, will be the main witnesses at a house committee hearing on the Mitchell Report after New York Yankees pitcher Andy Pettitte and two others were dropped Monday night.

Former Clemens teammate Chuck Knoblauch and convicted steroids dealer Kirk Radomski also were dropped from the witness list for Wednesday's public session.

One new witness was added Monday night — a lawyer who worked with former Senate majority leader George Mitchell to produce December's report on drugs in baseball.

But all attention will be focused on Clemens, a seven-time Cy Young Award winner, and McNamee, his former personal trainer, who alleged he injected the pitcher with performance-enhancing drugs.

"I guess it's showtime, isn't it?" Clemens' lead lawyer, Rusty Hardin, said in a telephone interview.

Earl Ward, McNamee's lead lawyer, declined to comment on the changes.

McNamee said in the Mitchell Report that he injected Clemens with steroids and human growth hormone at least 16 times in 1998, 2000 and 2001.

Clemens's denials of those allegations drew the attention of the House Committee on Oversight and Government Reform.

McNamee also accused Pettitte of using HGH, something Pettitte acknowledged he did do for two days in 2002 to deal with an elbow injury.

Before Pettitte spoke to committee lawyers under oath last week, Ward said he thought Pettitte would tell Congress he discussed HGH with Clemens between the 2001 and 2002 seasons.

With Monday's decision, Pettitte was spared the potentially difficult situation of having to deliver public testimony that could hurt the position of Clemens, a friend, past teammate and former workout partner.

Radomski has said he had no direct contact with Clemens, and Knoblauch's knowledge in the matter appeared to be peripheral.

Pettitte gave a sworn deposition last Monday, followed the next day by Clemens, and McNamee later in the week.

Knoblauch, a former major leaguer who was a Yankees teammate of Clemens and Pettitte, was interviewed by committee staff last month, while Radomski had been scheduled for a pre-hearing meeting with the committee Tuesday.

All five originally were invited to testify Wednesday.

"Mr. Knoblauch and Mr. Pettitte answered all the committee's questions and their testimony at the hearing is not needed," committee chairman Henry Waxman and ranking Republican Tom Davis said in a statement.

"Mr. Clemens and Mr. McNamee have also co-operated with the committee in its investigation."

Following Pettitte's deposition, his lawyers asked the committee to excuse him from the hearing, a person familiar with the talks said, speaking on condition of anonymity because the negotiations weren't made public.

Pettitte's request to be excused was first reported by The New York Times on its website.

Pettitte's Lawyer, Jay Reisinger, declined to comment after the announcement, while a lawyer for Radomski did not immediately return a phone message left at his office Monday night.

"I'm not disappointed," said Knoblauch's lawyer, Diana Marshall. "I know Chuck is not disappointed."

New witness summoned

The new witness is Charles Scheeler, a partner with Mitchell's law firm, DLA Piper.

According to the firm's website, Scheeler mainly works in commercial litigation and white collar criminal defence.

Asked about Scheeler's addition, Hardin said: "It's interesting. I look forward to hearing what he has to say."

Clemens' camp disputes several elements of the Mitchell Report's sections about him.

Clemens said he repeated under oath during his closed-door deposition what he previously had said in various settings publicly: "I've never used steroids or growth hormone."

McNamee, for his part, arrived for his deposition with colour photos of what his side says is evidence — and what Clemens' lawyers have called "manufactured" — that was turned over to the Justice Department last month.

McNamee's lawyers say the items include used needles saved for several years and that, when tested, they will prove Clemens used performance-enhancing drugs.

While McNamee has been quiet, not speaking a word to reporters after his deposition, Clemens has been crisscrossing Capitol Hill, speaking with nearly half of the members of the committee on a two-day tour last week.

The 45-year-old pitcher planned to meet with more lawmakers Tuesday, a day before he testifies under oath at the hearing.

Pettitte was supposed to be there, too.

Now the left-hander is free to get ready to head to spring training, as Yankees pitchers and catchers are to report Thursday.

"Every witness should make the decision that's best for them," Hardin said. "Roger plans to be there and to answer every question, fully and truthfully.

"Whatever anybody else did, that's their deal."