SPRINGFIELD, N.J. -- Earlier this week, while strolling through the tradition-rich Baltusrol locker room, Thomas Bjorn stumbled upon the record-setting scorecard from Jack Nicklaus' magical round of 63 in the 1980 U.S. Open.
"No matter where you go in the world, there's always a wall with Jack Nicklaus on it," Bjorn quipped.
So on Saturday, as Bjorn stood on the par-5 17th hole needing birdie-birdie to shoot 62 -- the lowest round ever in a major -- he turned to caddie Ken Comboy and filled him in on the potential for history.
"I told him 'Let's go for a 4 and a 3 and give the world a target,' " Comboy said with a grin.
It didn't happen. Bjorn settled for par on 17 and birdie on 18 for a final score of 63, tying him with Nicklaus and 21 others for the lowest round ever in a major championship.
After starting the day tied for 35th at 2 over, the 34-year-old European Tour player from Denmark shot his way up the PGA Championship leaderboard. It was a turnaround that few would have predicted -- Bjorn included. Over the course of a 12-year professional career, Bjorn's name has become more synonymous with catastrophic meltdowns and battles with inner demons than record-setting golf scores.
After double-bogeying the 18th at the British Open last month to miss the cut by one stroke, he sat down with instructor Simon Holmes and succumbed to "extensive changes" in his swing, designed to help Bjorn finish his backswing. In the past, when the pressure was turned up, Bjorn's mechanics were turned off.
The changes were so extensive that Bjorn accepted it might takes months to adapt. Holmes told him he wouldn't feel comfortable for a year. And yet here Bjorn is, a few weeks removed from his first lesson, contending for the first major championship of his career and the first by a European since Paul Lawrie's British title in 1999.
"Guess I'm a bit further along than I thought I was," Bjorn said Saturday. "Now I just need to keep it up."
Everyone will be expecting a meltdown. After all, it was Bjorn who was leading the European Open back in July when he made 11 on the par-4 17th at The K Club, finishing with a final-round 86 for 33rd place.
It was Bjorn who lost the 2003 British Open at Royal St. George's after blowing a three-stroke lead with four holes to play. Everyone remembers the two shots he left in the greenside bunker on 16, causing double-bogey, but he also bogeyed 15 and 17, eventually losing by one stroke to Ben Curtis.
It was Bjorn who walked off the course at the 2004 European Cup, citing "too many demons" in his head.
It was the same Bjorn who again fell apart at St. Andrews, hitting his tee shot out of bounds on 18, prompting him to seek help from Holmes. Bjorn can't promise that Sunday at Baltusrol will be any different. But he came here with no expectations and despite shooting his jaw-dropping 63 -- a one-round score two shots better than anyone else in the tournament -- that isn't going to change.
"I'm going to stick to the things that I stuck to these first three days," Bjorn said. "Stick to trusting my golf swing, stick to playing my game and don't get carried away with the situation I'm in. I came in with no expectations and that's what I'm going to keep doing tomorrow, to stay in the moment and focus on making great golf shots because that's what's working."
Holmes believes his pupil can win with his new swing. Half the battle, he said, is getting players to accept such radical changes. When Bjorn called Holmes for help, the instructor dug out some old tape of the golfer, showing him that he wasn't finishing his backswing consistently. And when he failed to do so, the ball sailed to the right. Bjorn bought it. And continues to do so.
"If you work on the cancer of your swing, you're going to get at least five percent better before you even step on a tee," Holmes said. "If he started at zero, I'd say he's already up to 75 percent because he's focused on the right things. It will just take him a year until it becomes unconscious."
But time for such acclimations don't exist. On Sunday afternoon, Thomas Bjorn will step to the first tee of the PGA Championship and take his final exam. The temperature again is expected to hover at 100 degrees, the entire world will be watching and the new swing will be put under a microscope greater than any Bjorn ever expected.
The question remains how he -- and that swing -- will respond.
"The more often I put myself in that position," Bjorn said, "one day it's going to break my way."
Wayne Drehs is a staff writer for ESPN.com. He can be reached at Wayne.Drehs@espn3.com