Federal prosecutors in the perjury trial of former pitching ace Roger Clemens urged jurors on Tuesday to use common sense and not to fall for the "entangled web of lies" he weaved to protect his reputation.

Clemens, 49, is on trial for the second time on federal charges of lying in 2008 to the House of Representatives' Committee on Oversight and Government Reform, which was investigating drug use in Major League Baseball.

Prosecutors made closing arguments as jurors prepared to begin deliberations after nearly two months of testimony.

"What is this case about?" Assistant U.S. Attorney Gilberto Guerrero asked. "This case is not about Roger Clemens' greatness. It is about (him) lying...to protect his legacy."

Clemens, who won 354 regular-season games and is a record seven-time winner of the yearly Cy Young Award as best pitcher, is among the biggest names implicated in drug use in baseball.

The defense has worked to portray Clemens as a hard worker whose stunning late-career success was the product of dedication and smart pitching, not performance-enhancing drugs.

Defense lawyers will make closing statements and the jury will begin deliberating later Tuesday or Wednesday morning on what they have heard from 46 witnesses in the nine-week trial.

Guerrero outlined the government's charges against Clemens, including obstruction of Congress, making a false statement and perjury, and appealed to jurors to use their common sense.

He argued against attacks on the testimony of Brian McNamee, the prosecution's key witness and Clemens' former trainer, who said he injected Clemens with anabolic steroids and human growth hormone between 1998 and 2001.

Clemens' lawyers have worked to paint McNamee as a liar who obtained immunity in exchange for his testimony.

"We're not asking you to like Brian McNamee. ... Brian McNamee did a lot of things that weren't nice ... but Roger Clemens is the one who chose Brian McNamee to inject him with steroids and HGH," Guerrero told the jury.

He also highlighted inconsistencies in defense witnesses from Clemens's wife, Debbie, who testified that she had received an injection of human growth hormone from McNamee in 2000.

New York Yankees' pitcher Andy Pettitte testified earlier in the trial that Clemens, a former teammate, told Pettitte in 1999 or 2000 that he had taken human growth hormone but, years later, said he had been referring to his wife's use of the drug.

Guerrero pointed to physical evidence prosecutors have presented, medical waste which they say contain Clemens DNA and traces of steroids. Defense attorneys have argued that blood and pus on two cotton balls and a small number of cells on a needle, could have been fabricated.

"That's totally illogical. There's no way in the world someone could fabricate that," Guerrero said, echoing the testimony of a government forensic scientist.

McNamee testified that he kept needles, cotton balls, a broken steroid ampoule and other medical waste from injections for Clemens. He turned the evidence in to authorities in 2008.

Clemens won his final Cy Young Award in 2004, the summer he turned 42, in his first season with the Houston Astros.

(Editing by Doina Chiacu)