TUCSON, Ariz. — For the second year in a row, Randy Johnson begins spring training recovering from back surgery.

At 44, he said this almost certainly will be the last of such comebacks.

"I don't care to go through another surgery again, and rehab," he said today. "If this was to happen again, it's 99.9 percent" that he would retire.

One of the game's greatest left-handed pitchers is heading into the final season of a two-year, $26 million contract he signed with the Diamondbacks after being traded back to Arizona from the New York Yankees.

When his back held up for a time a year ago, he had six strong outings. And he is 16 wins shy of 300 for his career.

Johnson will not say whether, if he makes it through this season, he will hang it up. But he said he wants to end his career "on my own terms."

"I've played 25 professional years, and this might be my 20th or 21st major league spring training," Johnson said during a lengthy session with reporters. "Just a matter of playing that long is quite an accomplishment. ... I just want to be able to walk away from the game and say 'You know what? I finished up healthy.'"

Johnson enters spring training this year in much better shape than a year ago. It's been six months since he underwent surgery in early August to correct a herniated disc. Last year, it had been just over three months, and he acknowledged he may have pushed himself too quickly.

"It's a freak thing that happened, and there's no guarantee it won't happen again," he said, "but the one thing that is good is that I've taken plenty of time to let it heal up."

Johnson wound up 4-3 with a 3.81 ERA in 10 starts last year. In his final outing, on June 28 against the Los Angeles Dodgers, he lasted three innings. He said Saturday he knew then his season was finished, and he was headed for the third back surgery of his career.

Because of his age, retirement seemed a reasonable possibility. But Johnson quickly vowed to come back.

He already had three bullpen sessions in Phoenix before Diamondbacks pitchers and catchers reported on Friday.

"Clinically he feels good. His arm feels great," general manager Josh Byrnes said. "It's a matter of defying some recent history and Father Time a little bit. But there was a six-start stretch last year where he was as good as anyone. It's clearly worth everyone's time to try to get Randy on the mound and try to be smart about it."

A healthy Johnson would add to an already strong Arizona rotation headed by 2006 Cy Young Award winner Brandon Webb and Dan Haren, acquired in the offseason from Oakland. Byrnes and manager Bob Melvin have talked about making Johnson the No. 2 pitcher between Webb and Haren, although that has yet to be determined.

Johnson knows he's not the pitcher he was in his prime, but then again, few have reached that kind of success. In 22 big league seasons, Johnson is 284-150 with a 3.22 ERA. In 2002, he achieved the "triple crown" of pitching, leading the National League in wins, strikeouts and ERA. His 4,616 strikeouts ranks first among left-handers and third overall on baseball's career list, behind Roger Clemens and Nolan Ryan.

Asked about Clemens' testimony before a congressional committee Wednesday, Johnson compared it to "reality television." He said he thought the House members should have done a little more homework to come up with more insightful questions than what uniform Clemens would wear going into the Hall of Fame.

As for the Mitchell Report on drug use in the sport, Johnson said he thought baseball was moving in the right direction but added he had not paid too much attention to the issue while focusing on his rehabilitation.

Although he is 6-foot-10, Johnson evolved into a power pitcher with amazing control. In 1999 with the Diamondbacks, he threw 271 2-3 innings, striking out 364 with 70 walks.

"He's a freak of nature as far as what he's done, what he's accomplished," Melvin said. "His arm's in great shape. That's never been a factor. It's just been a back issue."

Last season, even with his back woes, he struck out 72 and walked just 13 in 56 2-3 innings.

"It was a lot easier when I was throwing 95 to 100 mph," he said. "Now I find it a lot more of a challenge to get major league hitters out with what I have. I still think I can go out there and dominate at times. I may just not do it on a consistent basis in 25 out of 35 starts as I once did."

Johnson said: "I like to prove people wrong."

Succeeding at age 44 after two back surgeries in less than a year would satisfy that desire.

"According to a lot of the experts out there, I probably shouldn't even be playing the game anymore and shouldn't have been playing it about three or four years ago," he said. "The experts once again said there are going to be no more 300-game winners. I just have to go out and be healthy, and I'll take my chances."