Donald gives Memorial another No. 1.

DUBLIN, Ohio (AP) - Jack Nicklaus played his last round in a major alongside a 27-year-old from England with a quiet demeanor and efficient game. He had no idea that Friday afternoon at St. Andrews that Luke Donald one day would be No. 1 in the world.

Is he surprised six years later to see Donald atop the world ranking?

Not from what Nicklaus has seen in recent months.

Nicklaus, as he does with most tour players who move to Palm Beach County, offered Donald a membership at The Bear's Club, which has one of the most complete practice facilities around. Donald has been putting it to good use.

"Luke's game has come a long way," Nicklaus said. "But I will have to tell you that Luke is a member at The Bear's Club down in Florida, and he's there all the time. There isn't anybody who spends more time working on his golf game than I've seen in Luke Donald. And he spends his time chipping and putting, chipping and putting. I mean, he wears out the practice greens.

"And I think that the effort he has put into it has been rewarded."

The rewards are more than even Donald once imagined. By winning the BMW PGA Championship at Wentworth in a playoff over Lee Westwood, he became only the 15th player to be No. 1 in the 25 years of the world ranking.

It was his second win in three months against a world-class field, to go with a playoff loss at Hilton Head and another runner-up finish in the World Match Play Championship in Spain. Donald hasn't finished out of the top 10 - a streak of nine tournaments - since he missed the cut at Riviera in his return from a three-month winter break.

Donald makes his debut as the new No. 1 on Thursday, when he tees off at the Memorial with the last two Masters champions, Charl Schwartzel and Phil Mickelson.

The field also includes Rory McIlroy, Steve Stricker, Dustin Johnson, Nick Watney and Players champion K.J. Choi. Missing is Tiger Woods, who is recovering from left leg injuries.

Donald is not a physically imposing figure - not along the lines of Woods, Vijay Singh or Martin Kaymer - yet there is no disputing the results he has put together over the last two years. He only has three wins, but he has finished in the top 10 in just over 50 percent of his tournaments.

Most importantly, he feels like he's No. 1.

"I do," Donald said. "I think the way that the world rankings are, consistency is highly weighted. If you can keep playing well week in and week out, keep earning those points, then you're going to climb in the world rankings. And I don't think there's anybody who has been more consistent in the last nine months than me."

There's another factor that Donald willingly points out: Woods' downfall has given the rest of golf a fighting chance. That's one reason Donald never spent much time dreaming about being No. 1 in the world. With Woods around, it didn't seem mathematically possible.

"As a kid you dream about winning majors and winning tournaments," he said. "But for me, I always kept an eye out on the world rankings and had an interest in it. But I supposed for the bulk of my career, Tiger was so far ahead that it never really crept into my mind.

"But in the last year or so, there's been more of an upheaval in the rankings, and there's been a lot more movement. So I knew the opportunity was there."

With Woods out of the way - he slipped to No. 13 this week - Donald, Westwood and Kaymer have been No. 1 over the last three weeks. That's the highest turnover in the ranking since 1997, when Woods, Ernie Els and Greg Norman took turns over three weeks. Woods eventually established himself as the undisputed No. 1 in the ranking.

This could take longer to sort out, although Donald is in the right place.

He reached the top in style, winning the European Tour's flagship event despite not having his best game on the weekend, and beating the former No. 1 in a sudden-death playoff.

"I would have loved to have won by 10 and not had to go through all that stress," Donald said. "I didn't have my best golf last week. I think that's what was more satisfying to me than anything else, that even without really feeling totally in control of my game, I was able to get it done. And obviously, to do it in that circumstance, going head to head with Lee and to have everything on the line, made it that much more special."

The last time No. 1 changed hands with the top two players going head to head was at the 2004 Deutsche Bank Championship, although Vijay Singh easily defeated Woods in regulation without having to go to a playoff.

The biggest change for Donald was a short game and the shortest space in golf - between the ears. Along with working on his fitness following a wrist injury in 2008, he hired performance coach Dave Alred, best known in rugby circles as a kicking coach for the likes of Jonny Wilkinson.

Kaymer, after losing to Donald in the final of the Accenture Match Play Championship, said Donald's short game was better than Mickelson's. Along with trying to keep it in the fairway to compensate for his lack of power off the tee, Donald has worked endlessly with longtime coach Pat Goss on chipping and putting.

Nicklaus, the tournament host at Memorial, can attest to that from what he sees at The Bear's Club.

"I've worked very hard down there," Donald said. "They have such great facilities that I feel guilty if I don't work hard."

Does he ever see Nicklaus hitting balls?

"Not very often, no," Donald said with a smile. "I think he spends a lot of time on the tennis courts."