Nichols Leading Jacklin : Senior golf: He shoots a 64 for a one-stroke edge over the former U.S. and British Open champion.

Tony Jacklin, who won the U.S. Open and the British Open while playing golf’s regular tour, prepared himself for the Senior PGA Tour in a most irregular fashion, even by golf standards.

He took 10 years off, but he didn’t play like it Friday in shooting a six-under 65 to trail Bobby Nichols by one shot after the first round of the Ralphs Senior Classic at Rancho Park.

It might not be the right approach for everyone. Then again, there are a lot of things a golfer can do in an entire decade of not playing in tournaments.

Like these: Whittle a golf cart out of a tree trunk; embark on a lecture tour (‘Why Graphite?’); fashion golf balls out of Milk Duds painted white and baked in a kiln.

All Jacklin did was go from 40 to 50. Once he became eligible for the seniors, Jacklin grabbed his clubs and started swinging. His fourth time out, he won.

Jacklin’s victory in the First of America Classic at Grand Rapids, which he entered with a sponsor’s exemption, was his first in a PGA Tour event of any kind since 1972.

Nichols, who had six birdies in a row from No. 6 to No. 11 on Friday, could go no lower than a 64, which he was pretty proud of anyway.

“It hasn’t been a very good year for me, but this sure beats the heck out of working,” he said.

Nichols said Rancho Park is one of the tour’s hardest in pitching the ball on the green, but he birdied No. 8 and No. 9, back-to-back par fives, with pitching wedges that got the ball to within eight feet and three feet of the hole.

He also pitched to three feet and made par after missing the fairway and the green on No. 18.

If Nichols thought the greenside rough was tough, he wasn’t really complaining, though, mainly because he has seen it all before. He played the 1961 L.A. Open at Rancho Park.

A group of five was at 67, three shots behind Nichols, including 1993 Senior PGA champion Tom Wargo.

Thirteen more shot 68, including leading money winner Dave Stockton and last week’s champion, Bob Murphy. Raymond Floyd shot 69 and is five shots back in a group that includes Jim Albus, Miller Barber, Lee Elder and Bob Charles.

Jacklin proudly pointed to his 65.

“That’s my lowest round round of golf in 12 years, in or out of competition,” he said.

Mostly, he has been out. Jacklin gave up his PGA Tour privileges in 1973 to return to England and concentrate on the European Tour. He captained the Ryder Cup team in 1983, 1985, 1987 and 1989.

In almost no time, he was 50, he felt like playing golf again and was ready for the senior tour, moving to a new home in Palm Beach Gardens, Fla.

Jacklin’s rookie senior season has spanned 12 events, three top-10 finishes and $187,172 in prize money. After being away for so long, Jacklin knew it would be difficult, and it has been.

“The hardest is the mental part of it,” Jacklin said. “The mental discipline of tournament golf. That’s what it’s all about, really. When you don’t play 10 years or 50, you get out of the habit of it.”

Jacklin is trying hard to readjust. It promises to be an ongoing effort, but that’s how golf works, said Jacklin, who finds its quirky nature both appealing and frustrating.

“You never really win,” he said. “It’s a challenge between you and the elements to make the best of it.

“That’s the fun of it. That might sound a bit masochistic, but that’s what we do.”

So that’s why. No wonder Jacklin is back at it, playing golf again. He couldn’t stand thinking of all the pain he was missing.