Both signed for four-under-par 67s – the same as Matteo Manassero – as Magnus Carlsson, a 28-year-old Swede, set the early pace in the race for a 27,000 top prize with a 65 that contained ten birdies over the heather-fringed Aviemore course.
Out in the fourth group of the day at just after 7am, former Scottish Amateur champion Murray bagged six birdies, including the 17th and 18th, and was in a hearty mood as he headed off to celebrate his birthday declaring: "It's time for the cake and candles!"
The Anstruther man, a professional since 2006, finished third in the Madeira Island Open on the European Tour earlier in the season but has yet to register a top ten in his five appearances so far on the Challenge Tour this year.
"I have been playing well for a while now, just not putting great," he commented. "I played in The Open qualifier at Sunningdale (on Monday] and hit the ball great but just could not make a putt so I have been working on it a lot since I came up here and the putting stroke seems to be getting better."
Wearing a Ben Hogan-style bunnet that has become his trademark in recent seasons, Doak also made his score with a strong finish, the 32-year-old from Greenock picking up three birdies in the last four holes to come home in 33.
Ahead of the two Scots on the leaderboard are a Swede (Carlsson), a Finn (Antti Ahokas), an Englishman (Matthew Cort), a Dane (Thorbjorn Olesen), a Norwegian (Marius Thorp), two Frenchmen (Francois Calmels and Charles-Edouard russo) and a Chilean (Mark Tullo).
Carlsson, back on the Challenge Tour after he also lost his card for the main circuit at the end of last season, only had five pars on his card and would have been more than just a shot ahead of the chasing pack but for a double-bogey 5 at the 16th, where he found himself with a "terrible stance" in a greenside bunker and failed to get out at the first attempt.
Playing with defending champion Jamie McLeary, who had a level-par 71, Manassero had Steve Surry's course record of 64 in his sights after storming to the turn in five-under 30, the 17-year-old Italian having picked up six birdies in that stretch, including four in a row from the fourth, where he holed a bunker shot.
However, last year's Open Championship Silver Medal winner walked off the course looking deflated after coming home in one-over. "I felt I deserved better than 67 but I would have taken that at the start of the day."
Cort, a 35-year-old from Leicester, blazed home in 31, one less than Ahokas posted over the same stretch, while Thorbjorn's effort was, according to one of his playing partners, the "easiest five-under round" he'd ever witnessed.
On a day when less than 40 players in the 153-strong field managed to break par, Englishman Michael Lowe ran up a painful 12 at the par-4 11th as he limped home in 47, though at least he made it to the first tee. Compatriot Graham Povey suddenly felt dizzy shortly before he was due to set out and, after initially being treated by on-course medics, was taken by ambulance to a local hospital.