SAN DIEGO -- If Woody Williams pitches into his mid-40s, perhaps he can look back at March 31 as a key date in extending his career.

On the penultimate day of spring training, the Padres were in Las Vegas to play the Chicago Cubs, and Williams was on the mound for his final exhibition outing. Ordinarily, this would be an opportunity for him to fine-tune his mechanics and pitches for the regular season.

These weren't ordinary circumstances, however. The day before, manager Bruce Bochy had told Williams that he would begin the year as a reliever to make room in the rotation for spring sensation Dewon Brazelton. Williams wasn't in the best of moods.

He was in the mood to … experiment.

"I got put in the bullpen and I figured I might as well start jacking around," Williams said, only half-jokingly.

So Williams decided to reacquaint himself with an old friend -- the knuckleball. It's a pitch he taught himself as a kid playing catch with his buddies in Houston, but one he hadn't thrown since the early years of his career, with the Toronto Blue Jays.

"I've been throwing it my whole life," said Williams, who isn't sure whether he will use the pitch today in Florida, when he returns to the rotation to replace the injured Shawn Estes. "I have confidence with it. I think I can throw it for a strike just as much as anything else. The mechanics and release point are all that matters as far as location. It's just another pitch."

Beneath the bright lights of Cashman Field, Williams dusted off his knuckler. In two scoreless innings in relief of Chris Young, he threw four knuckleballs, and three of them resulted in strikeouts of Cubs batters.

"They were shaking their head," he said.

Also shaking his head, but in a good way, was the person on the other end of Williams' fluttering balls that night in Las Vegas. Before he came to San Diego in a December trade with Boston, Doug Mirabelli was the personal catcher for Red Sox knuckleballer Tim Wakefield, the only remaining specialist of a dying art.

Mirabelli declined to comment on Williams' new pitch -- he said he wants to keep it a secret from hitters -- but he told Padres pitching coach Darren Balsley that it's "excellent."

"He's a pretty good guy to trust," Balsley said.

Balsley wasn't as surprised by Williams' knuckleballs as the Cubs were. The two were roommates as pitching prospects on Toronto's Double-A team in 1988, and Balsley recalls his struggles trying to catch the pitch when they would toss a ball around.

"He doesn't have to change his arm action with it," Balsley said. "It's not your generic type knuckleball that's a big dropper. It's more of a dancer, a little bit harder than most guys throw. But he has good command of it. It's a useful pitch."

The Blue Jays discouraged Williams from incorporating the knuckleball into his minor-league repertoire, preferring that he develop an effective change-up as an off-speed complement to his fastball. But he never lost his ability to throw the pitch.

"I didn't know that I'd have 13 years in the big leagues doing it the conventional way," Williams said. "I've been blessed as far as that's concerned."

Williams, who will turn 40 in August, said his right arm feels stronger now that it did two years ago, when he won 11 games for St. Louis and was the Cardinals' Game 1 starter in the World Series. If he turns to the knuckleball this season, it will be on rare occasions -- Balsley suggested 5 to 10 percent of the time, and not on crucial counts where a mistake could burn him.

When his high-80s fastball loses a bit more juice, however, Williams will consider a late-career second act as a full-time knuckleballer. It's a small club -- Wakefield, 39, is the only active member after Steve Sparks failed to make the Padres out of spring training last year.

Going back into history, the non-taxing nature of the knuckleball has allowed many pitchers to delay retirement. Phil and Joe Niekro, Charlie Hough and Hoyt Wilhelm all pitched past the age of 43, with Wilhelm lasting until a year short of 50.

"I still don't think I'm to the point yet where I have to be reaching for something, regardless of what anybody else thinks," said Williams, who was 9-12 with a 4.85 ERA for the Padres last season. "I personally think I can still pitch the way I was brought up to pitch. If I have to fall back on something, yes, (the knuckleball is) very nice to have in my bag. I feel I can go out there and throw it every pitch and be successful."

PADRES NOTE -- 1B Ryan Klesko had arthroscopic surgery on the AC joint of his left shoulder Monday at Scripps Clinic. Klesko is expected to miss between two and four months.

Contact staff writer Brian Hiro at b_hiro@hotmail.com.