Federal prosecutors told jurors Wednesday morning that former super-star pitcher Roger Clemens took performance-enhancing drugs to lengthen his playing career and then lied about it to Congress because he was worried about his legacy.

Assistant U.S. Attorney Steven Durham also told jurors in opening statements during Clemens’ perjury trial that prosecutors would prove their case by presenting testimony from 45 witnesses, as well as forensic evidence, including tests that link Clemens’ DNA to needles used to inject him with steroids.

Baseball “is a very competitive sport,” Durham told jurors, adding that players “enjoy the recognition. They enjoy it for the money. They enjoy a kid’s game played by an adult. Why be dishonest about it? To admit something like this would have a negative influence” on Clemens’ legacy and desire to make the Hall of Fame.

“This is something that Mr. Clemens wants,” Durham said.

Charged with perjury, obstructing Congress and making false statements, Clemens is accused of lying about taking steroids and Human Growth Hormone in 2008 to a Congressional committee investigating the prevalence of performance-enhancing drugs in baseball. His trainer, Brian McNamee, testified that he had injected Clemens with those substances with the pitcher’s knowledge between 1998 and 2001.

The House Committee on Oversight and Government Reform held the hearings because it was concerned about whether young players might start taking steroids if their starts were using the substances. “The committee’s goal was to protect these young people from dangerous drugs and dangerous influences,” Durham said.

It then called Clemens to testify after the former pitcher publicly denied allegations made in a 409-page report authored by former Sen. George Mitchell that Clemens had taken steroids and Human Growth Hormone. It was during those hearings that Clemens is accused of lying about having taken performance-enhancing drugs.

Clemens’ defense lawyer, Rusty Hardin, is to make his opening statement later Wednesday.