The eight-time European number one went to the turn at four under at Gullane and a birdie at the 12th extended his advantage.
However, testing conditions made it difficult coming home and four bogeys in five holes dropped him back before a 15-foot birdie putt at the last saw him close with a 69.
That put the Scot in a group on two under, one shot behind early leader Klass Eriksson with 18 holes to play, as he chases a return to the Open for the first time since 2009.
Just 12 places - three at each of the four courses hosting local final qualifying - are up for grabs.
Kent Challenge Tour professional Steven Tiley, who has played in two of the past three Opens and finished 68th at St Andrews in 2010, put himself in a strong position to secure one of those prized berths at The Musselburgh.
He set a stunning pace with a seven-under 64 to open up an early four-shot lead after his first 18 holes.
Over at North Berwick, Edinburgh-based James McCleary's blemish-free round of 66, which included five birdies, put him out in front.
It was one better than Michael McGeady and Australian Daniel Gaunt and while Oswestry amateur Will Jones had a hole-in-one with an eight iron on the 172-yard par-three 10th his four-over total for 18 holes will be too far back for him to have an impact with his second round.
Dubliner Colm Moriarty led at Dunbar after three birdies in his final four holes allowed him to post a five-under 65, one ahead of Worcester's Oliver Farr.