For most of Thursday, Henrik Stenson seemed to be the inevitable first-round leader of the Masters. He made two eagles on the front side, used a birdie at 15 to get to 6-under par for the tournament and was two shots clear of the field.

“What Henrik was doing early, that was pretty impressive,” Tiger Woods said.

He stumbled a bit with a bogey at 16. But when he stepped to the 18th tee, he suddenly devolved into the man who became so distraught with his game — way back in 2001 — that he walked off the course mid-tournament. He sent his drive so far left, it flirted with a concession stand. He twice hacked through the pine straw just to get back to the fairway, then sent his approach well over the green.

“It went from bad to worse on 18,” Stenson said.

A chip, a putt from the fringe, a miss from three feet and a tap-in later, he had a round-souring, quadruple bogey 8 — sending him from 5 under to a 1-under 71.

“I’ve got a temper, but it’s almost like I got past that stage,” Stenson said calmly.

‘Administrative error’

World No. 1 Luke Donald three-putted the fifth hole for a bogey 5, a simple stumble en route to his 3-over 75.

“I three-putted 5 and three-putted 6, and [at] 2 over at that point, just sort of playing catch-up,” Donald said immediately afterward.

But when his score from the fifth was entered into Augusta National’s computer system, it somehow became a birdie 3 — and left open the possibility that Donald had signed an incorrect scorecard, which would have left him disqualified from the tournament.

After an investigation, club officials admitted an “administrative error” in the case, and Donald remained in the field.

Obama supports women

President Obama believes Augusta National should admit women, White House press secretary Jay Carney told reporters Thursday in Washington.

With the club’s policy to remain all-male again in question leading up to this week’s Masters, Obama, Carney said, understands that it is the private club’s decision, his “personal opinion is that women should be admitted to the club.”

“The president answered quite clearly to me that he believes Augusta should admit women,” he said. “We’re long past the time women should be excluded from anything.”

Republican presidential candidate Mitt Romney, meanwhile, told reporters in Pennsylvania: “If I could run Augusta, which isn’t likely to happen, of course I’d have women.” . . .

Mark O’Meara, the 1998 Masters champion who hasn’t made the cut here since 2005, pulled out of the tournament before teeing off with a pulled muscle in his ribs, according to the PGA Tour. O’Meara played nine practice holes with his friend Woods on Wednesday, and then participated in the par-3 contest.