Roger Clemens' chief accuser is expected to testify against the former pitcher. It will be a make-or-break moment for the prosecution as it seeks to convict Clemens of perjury.
Brian McNamee, Clemens' former strength coach, takes the stand Monday as the trial moves into its fifth week. McNamee says he injected the seven-time Cy Young Award winner with steroids and human growth hormone in 1998, 2000 and 2001.
Clemens is accused of lying to Congress when he denied using those drugs.
The judge in the Roger Clemens perjury trial may be on the verge of letting the government show the former pitcher's largely baseball-ignorant jury just how widespread steroids and human growth hormone were in the sport.
The move is one that Clemens' lawyers would like to avoid, but may have brought on themselves.
Clemens is on trial for allegedly lying in a 2008 congressional deposition and hearing when he said he never used steroids or HGH.