By Ian Simpson

WASHINGTON (Reuters) - New York Yankees pitcher Andy Pettitte, a key witness against former teammate Roger Clemens in his perjury trial for alleged use of performance-enhancing drugs, testified on Tuesday that Clemens had been his longtime friend and mentor.

Pettitte is one of the most anticipated witnesses in trial of Clemens, charged with lying to Congress in 2008. Both Yankee aces had worked with the same personal trainer, Brian McNamee, another important figure in the case.

Pettitte has admitted using human growth hormones in 2002 and 2004. He also testified to a congressional committee that Clemens told him in 1999 or 2000 and then again in 2005 that he had used human growth hormones. Clemens told the panel that while Pettitte was a close friend, he "misremembers" the conversations.

"We hit it off immediately" after Clemens was traded to the Yankees from the Toronto Blue Jays in 1999, Pettitte, 39, told jurors. "We had the same agent so we had a connection there ... It was a good situation."

Under questioning from prosecutor Steven Durham, Pettitte said he had considered Clemens a mentor and would go to him for advice.

Asked if he had affection for Clemens, Pettitte said, "Yes," all along not looking at his former teammate.

Clemens, 49, a seven-time winner of the Cy Young award, baseball's highest annual honor for a pitcher, watched Pettitte without emotion, sitting forward in his seat at the defense table.

Pettitte and Clemens, both high school stars in Texas, both stars with the Yankees and Houston Astros, worked out together during the off season and often acknowledged their close relationship over the years.


Pettitte, the second witness in the case, was something of a surprise since prosecutors have not disclosed the order of appearance of their witnesses.

Clemens is being tried for a second time on federal charges of lying to the House of Representatives Committee on Oversight and Government Reform in 2008 about whether he used anabolic steroids and human growth hormone. The panel was investigating drug use in Major League baseball.

The trial of Clemens is expected to last about six weeks.

Clemens first went on trial last July, but Judge Reggie Walton declared a mistrial because prosecutors showed jurors a video clip that included material he had banned from the case unless it was raised by Clemens' defense team.

Pettitte has come out of retirement to bolster the Yankees' pitching staff and is playing his way back into shape with a Yankee farm club.

Pettitte took the stand after Hardin, Clemens' attorney, finished questioning the first witness, former Oversight Committee chief of staff Phil Barnett.

Barnett said he had had "serious doubts" about the accuracy of Clemens' deposition before the panel on his use of human growth hormone.

(Editing by Paul Thomasch and Philip Barbara)