Mickelson played his first four holes in 2 over at Gullane Golf Club, and while he rallied back with four subsequent birdies he ended with a 1-under 69 in the opening round. That score left the southpaw six shots off the early pace set by Denmark's Thorbjorn Olesen.
Making his first start since the U.S. Open, Mickelson followed a bogey on No. 3 with another bogey on the par-4 fourth. He bounced back with a birdie on No. 5 to make the turn in 1 over, then added circles on Nos. 10, 15 and 16. After finding the green on the par-3 17th, Mickelson three-putted from across the green and then failed to birdie the home hole from close range.
Mickelson won this event two years ago at Castle Stuart, then went on to lift the claret jug the following week at Muirfield. He remains the only player to pull off the impressive double, though his chances of victory this week are now dampened with more than 50 names already ahead of his in the standings.
Mickelson played in the afternoon wave, where scoring conditions were more difficult than the morning. Each of the seven players at 5 under or better when Mickelson finished his round had come from the morning wave, while Lefty's threesome was rounded out by Marc Warren, who shot an even-par 70, and defending champ Justin Rose, who opened with a 4-under 66.