Coming off what he called some of the worst golf of his career, the zany Swede made two eagles while using a new putting grip and led by one stroke over Billy Andrade and David Peoples at renovated Riviera Country Club.
Turns out the biggest change wasn't the course. Parnevik, who has played all seven weeks on the PGA Tour this year and hasn't registered a top-10 finish, was walking past a mirror in his hotel room when he realized he wasn't rotating his hips properly.
Suddenly, drives that were going short and crooked became his chief asset.
That's not all. Parnevik was playing the pro-am Wednesday and, for reasons even he can't explain, decided to switch to a cross-handed grip for the first time in his life.
And not just any grip. He points his left index finger down the shaft and his right index finger over his left thumb, with his right thumb attached to his left wrist. It sounds like he should have been doing the hokey-pokey, but instead he was holing a lot of putts.
'Everything fell into place very nicely,' Parnevik said.
The only problem he encountered was his left elbow brushing against his ribs on the longer putts, but Parnevik found a quick solution.
'I take a deep breath to hold my stomach in,' he said.
Unconventional, yes, although it was difficult to argue with the results.
Parnevik made a 20-foot eagle putt on the first hole and decided this new grip just might be the answer, at least for now. He also holed a couple of 25-footers for birdie, and chipped in from the fringe on the 315-yard 10th hole for eagle.
He remembers making two eagles in consecutive rounds at the Volvo PGA Championship in England, but 'that's been it for the next 10 years. It doesn't happen very often.'
Esteban Toledo, raised in impoverished conditions in Mexico and a fan favorite in these parts, had a 67, along with Tommy Armour III.
David Duval and John Daly were among the late starters.
Parnevik has played Riviera well in the past, tying for 13th last year and finishing second to Kirk Triplett in 2000, the year he wore his bright pink pants in the final round.
The Swede dressed close to normal on Thursday, with chocolate-colored pants and an argyle sweater, but most of the attention was on his swing changes.
Parnevik had hip surgery at the end of 2000 and is still making some adjustments, such as rotating his hips more during the backswing.
'It hit me last night in the hotel room when I walked by a mirror,' he said. 'I thought maybe I should try that. My drives were much straighter and 30 yards longer.'
He had a 9-iron into the 463-yard second hole, and a wedge on No. 12 after hitting a drive that was about 325 yards.
The putting style was really bizarre. Parnevik has never gone left-hand-low, even while messing around on the practice green.
'When you're desperate, you're desperate,' said Parnevik, who was 134th in putting coming into the Nissan Open.
The season is young, but not for him. He hasn't missed a tournament yet, and figures he will wind up playing 10 in a row through the Honda Classic, where he is defending champion.
'I had a bet with my caddie that I won't take a break until we win on tour,' Parnevik said. 'The way I was playing, it looked like it was going to be a long year.'
For Andrade, this is a new beginning.
He missed the cut in his first three events, and his ego was further bruised when Titleist decided not to renew his contract for the year. Andrade showed up in Hawaii with a blank bag and no club contract, enough to make any 15-year veteran feel like he doesn't belong.
'It was tough to explain my situation,' he said. 'I've been with that company my whole career. But numbers are numbers, and someone had to get cut.'
He signed with Mizuno last week and feels like he's back in the picture.
'What I've done so far is irrelevant,' Andrade said. 'This is my beginning.'
Full-field scores from the Nissan Open