Only days after a late double-bogey cost him the British Open Championship, Bjorn was back on the European Tour and eager to put the memories of Royal St. George's behind him.
'You've sometimes got to face reality and say 'Yes, I made a mistake last week,' but my golf is certainly good enough and that's what I believe.' said Bjorn. 'Today certainly shows that my best golf is good enough to play with the best.'
Bjorn played the back half first and opened with three birdies over his first nine holes. The Dane found a greenside bunker at the par-4 second but unlike his difficulty in the sand at St. George's on Sunday, Bjorn hit out to the bottom of the cup for a birdie.
'If ever there was a shot five days too late, that was it,' said Bjorn.
At the par-4 third, Bjorn hit his approach to 20 feet and drained the putt to reach 5-under. He then dropped his second shot inside four feet at the fifth for the first of three consecutive birdies.
Bjorn found trouble with a bogey at the par-4 eighth but recovered at the very next hole. He left his approach within 25 feet and ran home the birdie putt to stand two clear of his closest competitor after Round 1.
'I probably haven't walked off a golf course ever in my life as happy as I did today,' said Bjorn. 'I am proud of what I did out there. It is not the easiest golf course in the world. I felt comfortable on the golf course. I holed a putt on the first hole and I was back in the swing of things.
'We are conscious that we play Open Championship courses that are the finest links in the world. This is right up there with the finest, finest links in the world. This is the most fair links course I have ever played.'
Campbell also played the back nine first and picked up four early birdies to go out in 32.
The New Zealander missed the green at the par-5 sixth but converted a putt from the fringe for an eagle. Like Bjorn, Campbell bogeyed the eighth but responded with an 18-foot birdie at the ninth for a round of 66.
'It's nice to get off to a good start for a change,' said Campbell. 'I am gradually getting better and better every week. Today was a prime example that my game was getting back.'
England's Paul Broadhurst finished alone in third at 5-under-par 67.
Phillip Price was one shot further back alongside Luke Donald, Gary Emerson, Stephen Gallacher, Simon Khan and Greg Owen.
Padraig Harrington, who is trying to become the first Irishman to win this event since John O'Leary accomplished the feat in 1982, finished five shots off the lead in a group at 3-under-par 69.
Defending champion Soren Hansen tallied four birdies and four bogeys to finish at even-par 72.