SAN FRANCISCO — With two recent back surgeries behind him, Randy Johnson is refreshed and focused on being a baseball player again this winter — rather than a pitcher limited to rigorous rehabilitation work, his case the past two offseasons.

The 45-year-old Big Unit has been playing catch for three weeks already — and, now, is busy preparing to join his new San Francisco Giants teammates come the start of spring training in February.

Johnson and San Francisco agreed to an $8 million, one-year contract Friday, giving the Giants one of the deepest starting rotations in baseball with three Cy Young Award winners. Johnson has won five Cy Youngs and is five victories away from No. 300.

"I'm well ahead of schedule than I was the last two offseasons," Johnson said Saturday during a conference call, noting he plans to be on the 2009 opening day roster. "It will be really nice to be in that position this year. ... To some degree I have silenced the critics and shown that I'm healthy."

The Giants are counting on that.

Johnson joins fellow Cy Young winners Tim Lincecum (2008) and Barry Zito (2002) in an intriguing rotation that also features promising right-hander Matt Cain and lefty Jonathan Sanchez. San Francisco becomes the first team with three Cy Young recipients since the 2002 Atlanta Braves with Tom Glavine, Greg Maddux and John Smoltz.

Giants general manager Brian Sabean believes his club could become a contender again in the NL West with the addition of Johnson. San Francisco expressed an interest in him from the start of free agency and had several productive conversations with his representatives to make it happen.

Johnson wanted to stay on the West Coast, and in the NL West if possible, to start his 22nd major league season. The Giants will be his sixth big league team.

"During this process, there was a great deal of interest in me, and that leads me to believe there are some people who still believe in me," Johnson said. "San Francisco was at the top of my list. I pitched against them three or four times last year and saw the potential they have."

Still, the Giants haven't reached the playoffs since 2003 and Sabean will continue looking to upgrade his offense. The tough part about that is there are more outfielders available than infielders, and the Giants need to fill out their infield.

Sabean figures that boosting the pitching staff with someone like Johnson could help compensate for a less-productive offense.

"It just sends a message if we're short-stacked in one area we're going to do everything we can to win games," Sabean said. "Simply put, we're proud to have Randy in our organization. He's here for one reason and that's to help us make a run at this division. He's still one of the most intimidating pitchers in baseball."

Johnson, who spent the past two seasons with the Arizona Diamondbacks, was born in Walnut Creek, Calif., about 30 minutes from the Giants' waterfront ballpark. He grew up in nearby Livermore.

San Francisco offered several things on Johnson's wish list: spring training in the Phoenix area, and a chance to stay on the West Coast and in the NL West so he can pitch near his current home in Arizona.

"I'm excited to come back to where I started my baseball career," said Johnson, who still has a brother and a sister in the area. "As a visiting player with the Diamondbacks, a couple of the reporters would ask me, 'Toward the end of your career, do you see yourself playing in the Bay Area?' It's always nice to come back and play there."

Johnson, who can earn an additional $5 million in performance bonuses, has 295 victories after going 11-10 with a 3.91 ERA in 30 starts last season.

He has 4,789 strikeouts, second on the career list to Nolan Ryan (5,714). The 6-foot-10 lefty made $16 million last season, when he struck out 173 and walked 44 after beginning the season on the disabled list. He made his 2008 debut in San Francisco on April 14.

The A's were among the other teams interested in Johnson, a 10-time All-Star who filed for free agency last month. He and the Diamondbacks had serious discussions about a new deal that could have kept him in Arizona, but the sides failed to reach an agreement.

The Giants turned to a youth movement this year and finished fourth in the NL West at 72-90.

Johnson certainly will help attract fans as he chases his 300th win. The Giants went 37-44 at home for their fourth straight losing campaign in San Francisco. They also failed to reach 3 million fans for the first time in the 9-year-old ballpark's history, probably in part because home run king Barry Bonds was gone.

Sabean has been busy rebuilding the roster, adding shortstop Edgar Renteria and relievers Jeremy Affeldt and Bobby Howry this winter.

Johnson might be willing to stick around, too. He isn't ready to say that next season will be his last.

"I don't think I want to, and people are going to go, 'My God, will you retire already?'" he said. "I'm not going to say I'm done because I haven't even started this year. I'm excited to start this year. The last two seasons have been very draining for me because I've had to come back and prove that I'm healthy."