WASHINGTON - Star-struck at 11 when he saw pitching great Roger Clemens, a 25-year-old man became a witness for prosecutors seeking to convict the former baseball player of lying to Congress.

At issue in Monday's session of Clemens's trial in federal court in Washington was a 1998 gathering at baseball player Jose Canseco's house.

Clemens has denied attending the pool party, and it's one of the false statements prosecutors allege Clemens made in his 2008 congressional deposition.

The witness, Alexander Lowrey, testified Monday that he saw Clemens at the Canseco party. Prosecutors showed several photos of the former pitcher in attendance, including one of the 11-year-old Lowrey next to a smiling Clemens.

Lawyers have indicated that the government might wrap up its case this week.

Clemens spent 24 seasons in the major leagues, pitching for Toronto, Boston, the New York Yankees and Houston.