WASHINGTON -- Brian McNamee testified in the perjury trial of Roger Clemens on Friday that the beer can he says he stuffed with needles, ampules and bloodstained gauze after injecting the former Yankees pitcher with steroids also included medical waste from another player's injection.

With Clemens' chief accuser on the witness stand for the fifth straight day, defense attorney Rusty Hardin sought to raise doubt about McNamee's handling and reporting of physical evidence he says he kept in his basement after injecting Clemens at his Upper East Side apartment in August 2001.

McNamee viewed a photograph of the evidence he saved and identified two vials, a needle and a cotton swab he said were not used on Clemens.

Hardin portrayed McNamee's statement -- the first testimony the jury had heard about another player's waste -- as another in a series of evolving stories.

"Mr. McNamee, isn't this a classic example of you making stuff up on the fly?" Hardin asked.

McNamee, of Long Beach, replied that he's always told federal investigators and prosecutors that the beer can also contained evidence of another player's human growth hormone injection.

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While McNamee did not identify the other player Friday, he identified him as former Yankees second baseman Chuck Knoblauch in a deposition before congressional investigators four years ago. U.S. District Judge Reggie Walton has barred the naming of the other baseball players that McNamee says he's injected.

Hardin asked why McNamee, "as a former police officer," would decide to mix potential evidence of one's player steroid injections with another's medical waste.

"I wasn't thinking that way," McNamee said. "I had no intention of using it."

McNamee said the items from the other player's injection were already in a pocket of his bag, and he was planning to throw them out but never got around to it.

McNamee said initially that he put the other player's medical waste in the beer can "give or take a week or so" after he had brought the can home from Clemens' apartment. After Hardin pressed for a firmer date, McNamee said he believes he put the other player's vials, needle and cotton swab in the beer can on the same night he saved Clemens' materials.

"Didn't you make up this whole story?" Hardin said.

McNamee answered no, adding, "It's never been asked that way before."

McNamee, who has testified that he injected Clemens with performance-enhancing drugs during the 1998, 2000 and 2001 baseball seasons, will return to the witness stand for redirect questioning by prosecutors when the trial resumes Monday morning.

Clemens faces perjury charges for denying his use of performance-enhancing drugs before Congress four years ago.