Williamson, the 1999 National League Rookie of the Year who turns 32 next Sunday, is scheduled to report to the team's spring training complex in Scottsdale, Ariz., on Wednesday with pitchers and catchers.
The right-hander spent his first four-plus seasons with the Cincinnati Reds and has also pitched for Boston, the Chicago Cubs, San Diego and then Baltimore last season.
He went 1-0 with a 4.40 ERA in 16 outings in 2007, missing time early in the season while on the disabled list with tightness in his throwing arm.
Clemens update: One of Brian McNamee's lawyers said he believed the Justice Department will open a criminal investigation into Roger Clemens' denials of doping.
Clemens gave a five-hour deposition last week to staff lawyers of the House Committee on Oversight and Government Reform prior to Wednesday's public hearing. McNamee, former personal trainer to the seven-time Cy Young Award winner, gave a seven-hour deposition.
"I think there will be a criminal prosecution after Wednesday, and that means there will be grand jury proceedings and subsequent proceedings," said Richard Emery, one of McNamee's attorneys. "I don't see there's any possibility that Brian has any jeopardy. I only see the possibility of Clemens getting investigated by Justice, whether or not Congress refers it."
Meantime, the chairman of a congressional committee said comments attributed to Clemens' lead lawyer Rusty Hardin could be interpreted as trying to intimidate a federal law enforcement official.
Hardin was quoted in Sunday's New York Times as saying it would be "brazen" and "unbelievable" if IRS Special Agent Jeff Novitzky, a key prosecutor in the BALCO drug cases, attends the hearing.
"If he ever messes with Roger, Roger will eat his lunch," Hardin was quoted as saying.
Red Sox: First baseman Kevin Youkilis and Boston agreed to a $3 million, one-year contract, avoiding a salary arbitration hearing. Youkilis made $424,500 last season, when he hit .288 with 16 homers and 83 RBI.
Dodgers: Mark Sweeney, whose 163 pinch hits are the second-most in big-league history behind Lenny Harris, is nearing an agreement on one-year contract to return to Los Angeles. The 38-year-old left-handed hitter led the majors with 24 pinch hits last season.