The 28-year-old was hurt playing out from the rough as he opened with a double-bogey six but he regrouped well to shoot a one-under-par 69 for a 12-under tally of 198.
Brooks is one ahead of Frenchman Raphael Jacquelin (64) and leads by two from American Rickie Fowler (66), Dutchman Joost Luiten (66) and Briton Tommy Fleetwood (67).
Englishman Brooks, ranked 528th in the world, is chasing the biggest payday of his career, and a place in next week's British Open at St Andrews if he can claim one of the three spots available to a top-10 finisher not already exempt.
"I know what lays ahead should I win tomorrow but I am going to go out there and continue what I have been doing this past three days," he told reporters.
"I know it could all be life-changing but I will try not to think about it," added Brooks who started the third round three strokes clear of the field.
Jacquelin carded the best score of the day as he looked to land the fifth European Tour win of his career.
Fowler is hoping to follow in the footsteps of U.S. Ryder Cup team mate Phil Mickelson who captured the 2013 Scottish Open title before winning the British Open a week later.
"Seeing what Phil did two years ago, and my decision to come over last year and also this year as well, it definitely makes sense to play here the week before the Open," said Fowler.
"I'm just getting acclimatised, getting the game ready and getting a few things straightened out."
Mickelson returned a 70 on Saturday and is well down the field on 207, three under.
(Editing by Tony Jimenez)
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