The 36-year-old Scot made further inroads on par at the 10th, 13th and 14th. His only bogey of the day came at the 12th and he capped his round with regulation figures at the last four holes.
Lee's tally of birdies was one behind the European Tour record of 12 held by Fred Couples, Ernie Els, Darren Clarke, Russell Claydon and Jeppe Huldahl.
"I would like to have had a heart rate monitor on," Lee told reporters after returning a 16-under total of 197. "From the first hole I don't think my heart got under 100 beats per minute.
"There were certain crucial putts that got the heart going and I don't think it ever slowed down. I'm still not really ready to relax."
Lee has been a professional since 1996 but has never finished higher than second in a tour event.
In joint second place on 199 were Spain's Alejandro Canizares (65), Victor Dubuisson of France (66) and Dane Thomas Bjorn (67).
(Writing by Tony Jimenez; editing by Stephen Wood)