Thursday’s first round of the PGA Championship should not have favored the northern born. That was some authentic Tennessee Williams heat and humidity out there.

And yet, who were your leaders? A pair of Wisconsinites, Steve Stricker (7-under 63) and Jerry Kelly (65), guys who grew up thinking summer was measured by the hour.

Stricker, the guy who grooves his swing in the off-season by hitting practice balls into the snow, was so at home at the steamy Atlanta Athletic Club that he established a competitive course record and became the 23rd player to shoot 63 at a major.

How do you tie the record for lowest round in a tournament that really matters? You miss a 10-footer on the last hole that would have meant a 62.

That 63 is one of golf’s magic numbers, a standard that Stricker claimed never troubled his mind as he surveyed his penultimate putt.

“Jimmy [Johnson, his caddie] told me after I missed the putt; he’s like ‘You know that was for the lowest competitive round in the history of major championships.’ And I’m like, ‘Oh, shoot, it was,’” Stricker said. That passes for an adrenalin high for Stricker.

A 63 was plenty good enough to get the rest of the field’s attention.

“Any time you’re 2 under at major you feel good,” said Davis Love III, who was that Thursday. “Until you look up at Stricker, and you feel like you’re at the John Deere Classic.” Stricker has won the past three of those, at a combined 68 under.

On Thursday, he mocked the two hardest holes on the course — the 253-yard par-3 15th, and the 491-yard par-4 18th — with birdies on both.

“That’s like stealing probably three or four shots from the field there,” Stricker said. He shot 30 on what most consider to be a treacherous back nine.

There was more form-bending news from the mean fairways of Johns Creek.

The AAC’s new beefed-up par 70, all 7,357 yards of it, was portrayed as the playground of the long and limber. And yet there were relative Lilliputians all over the leaderboard.

Stricker (116th in PGA Tour driving distance), Kelly (187th) and the third-place Shaun Micheel (130th) are hardly big hitters. Finishing one shot back of Micheel’s 66, Scott Verplank is 46 years old, maybe 5 feet 9 and does well to rank 180th in clout.

For one day, the steady approach trumped the spectacular.

“Look at the guys up there [on the leaderboard], they’re smart players. They’re not bombers and gaugers. You’re not going to survive doing that,” Micheel said.

All kinds of trouble lurks off the diamond zoysia carpet of these fairways.

There is enough water. Ask 19-year-old Japanese Ryo Ishikawa. He got wet six times on the way to an 85.

Savage roots lie in wait. U.S. Open champ Rory McIlroy chopped down on one early in his round and still managed a 70 with a right hand taped up as if he were getting ready to go 12 rounds with Manny Pacquiao. He went straight from the course to have his damaged wrist scanned.

And the bunkers apparently are filled with quicksand. Numerous players testified to their ball-eating properties.

Tiger Woods sampled the whole Pu-Pu platter of problems Thursday, shooting 77, his highest PGA Championship round ever. He began his day 3 under through five holes, then went 10 over for the last 13. A real Dow Jones round.

In Woods’ long absence, Stricker is the top American in the world golf rankings — No. 5. Yet he has little to no interest in being a flag-carrier here this week.

“No. I don’t want that pressure,” he said when asked if he might be identified as the best U.S. hope here this week.

He is the anti-Tiger, an accomplished player who has no interest in taking over the world. He is quite content to be a stealth millionaire.

He would, however, at the age of 44, dearly love to add a major to his 11 PGA Tour victories. The harder he has tried to squeeze one, the more it has squirted from his grasp.

At dinner last night with his good buddy Kelly, there would be little conversation about this elusive goal. “We don’t talk about golf too much,” Kelly said.

And on the course Friday, Stricker will try to continue a ruse he runs on himself at the majors.

“I keep trying to tell myself it’s like any other tournament,” he said. “We’re playing against the same guys we play against on a weekly basis. You try tricking yourself into thinking that there’s really nothing extra or different about this event — but knowing deep down that there is.”

Two kinds of heat, literal and symbolic, are present at this PGA Championship. A quiet man from Edgerton, Wis., must yet show he will melt in neither.