John Parry, ranked No. 471, held the clubhouse lead after a bogey-free 64 and Simon Khan (65) also tamed the Castle Stuart course in perfect morning conditions in the Scottish Highlands to finish alone in second.
Mickelson is tied for third with six others after quickly hitting his stride in the warm-up event for next week's British Open, finding his range on and around the greens to produce six birdies and an eagle.
Twenty-one years into a trophy-laden professional career, the four-time major winner insists there is still time for him to ''conquer links golf.''
And his stylish opening round suggested a first win in Europe since 1993 could come either here or a few hours south in Muirfield next week.
''It's great for me to get off to a decent start because I have gotten off to poor starts the last couple of years here, and I have been fighting just to make the cut and get into reasonable contention,'' said Mickelson, who at No. 8 is the highest-ranked player in the tournament. ''I'm not having to battle uphill.''
After a three-putt for a bogey on his first hole left him muttering, Mickelson made a 15-foot putt for eagle at No. 12 – his third hole. The decision to install five greens, all with different surfaces, in his garden to improve his putting is paying off this year.
''Many of my great rounds in the past have started with a bogey,'' Mickelson said, ''so I wasn't too worried.
''The very first shot I tried to get a little greedy and it comes back to bite me. So it was a good wake-up call.''
Mickelson, fresh off missing the cut at The Greenbrier Classic last week and the heartbreak of his runner-up finish at the U.S. Open last month, felt he still ''let a few shots go'' in his first round of links golf since missing the cut at last year's British Open.
The same can't be said of Parry.
Outside the world's top 600 in December, Parry is in his first year back on the European Tour after losing his card in 2011. His confidence improved with a surprise 28th-place finish at last month's U.S. Open – his first major.
''I played with some top players and saw what they are like – you realize you are not a million miles away, that they are just more consistent,'' Parry said.
Everything went right for him after going out in the second group at 7:40 a.m., with birdies on four of his first six holes. Picking up a shot at the last pushed him ahead of Khan, who had just finished as part of the first group, and left Parry with a grin on his face.
''It was one of them where it just keeps happening,'' said Parry, whose only tournament win came in the Vivendi Cup in 2010. ''You wonder why you can't do that every week.''
Shane Lowry, Mikko Ilonen, James Morrison, Kiradech Aphibarnrat all shot 66s with Mickelson in the morning session. Thongchai Jaidee and Chris Doak joined the seven-man group in a tie for third place a few hours later.
Only 14 of the 78 players setting out in the morning session finished over par, and 117 of the 156-man field broke par.
But with the wind picking up off the Moray Firth, the afternoon starters – among them the last two British Open champions, Darren Clarke and Ernie Els – found things slightly tougher and no one came close to threatening Parry's score.