At 7,665 yards Barseback, Stenson’s home course, is the longest in European Tour history.
The world number seven thought that would be in his favour, but he trails England’s Lee Slattery by six — and was relieved it was not by more.
“I played like a pig and got away with murder,” said Stenson. “I didn’t play well at all, but the little Seve and Houdini in me was out there.”
The Ryder Cup star was again wearing a green ribbon in his cap in support of an Iranian friend, as he did at The Open last week.
“It’s a symbol for democracy in Iran and I felt it was an important gesture.”
Slattery, ranked 497 places below Stenson, holds a one-stroke lead over Argentina’s Ricardo Gonzalez.
Ireland’s Gary Murphy is tied 12th after a two-under 71. Gareth Maybin and Michael Hoey are both one under. Peter Lawrie and Damien McGrange both fired par 73s.
Without a top 20 finish since he was fourth at the KLM Open in Holland last August, Slattery was first man to tee off at 7.30am and birdied the first four holes.
The last of those was a chip in and he did it again only two holes later before making a 10-footer on the long ninth to turn in a brilliant six under 30.
An hour-long suspension in play because of the threat of lightning took the wind out of the 30-year-old’s sails, but after bogeying the long 12th on his return, he got up and down from a greenside bunker at the 558-yard 16th and parred the last two for a six under 67 that kept him at the top of the leaderboard all day.
“The length of the course is ridiculous given the size of the greens,” he said after a round containing only 22 putts.
“I’ve not been playing my best and I woke up and just thought ‘enjoy it and trust your swing.’
“After making the start I did, it just felt like the pressure was off. The field is not as strong this week, so it’s a chance to do well and secure my card — although I’m trying not to think about that.”
Only the top 115 on the money list at the end of the season retain their membership and the Southport golfer is currently 136th. Two years ago he missed out by less than £60 and had to return to the qualifying school.
Australian Brett Rumford joined Slattery on six under, but then ran up a closing triple bogey seven after losing his first drive and being forced to chop out of the trees with his second.
Big-hitting Gonzalez has been struggling even more than Slattery this season and finds himself only 153rd in the “Race To Dubai’ standings. He did, however, finish 13th in the French Open this month and seven birdies boosted his confidence even more.
Joint third are his compatriot Tano Goya, Spaniards Pablo Martin and Pablo Larrazabal and Swede Klas Eriksson.
But New Zealand’s former US Open champion Michael Campbell, yet to make a cut all year, struggled to a 78.