Assistant U.S. Attorney Steve Durham said in opening statements to a Washington jury that Clemens "became trapped in a web of his own lies" in a "story of deceit, honesty and betrayal" when he denied using performance-enhancing drugs to a Congressional committee in 2008, USA Today reported.
The former fireballer faces perjury charges stemming from his appearance four years ago before a House of Representatives committee probing the use of steroids, human growth hormone and other banned drugs in major league baseball.
Prosecutors say Clemens made 15 false or misleading statements to the panel regarding his alleged drug use.
After jury selection was completed Monday, Durham told the court he would prove Clemens received injections from strength coach Brian McNamee, who trained the hurler while he was with the Houston Astros, the newspaper reported.
"All (Clemens) had to do was tell the truth and the evidence will show that he didn't," Durham said.