Lee was in total control on a day when he marked his card with 11 birdies against one bogey to enjoy a two-shot advantage with his three-day total of 16-under-par 197 at the €2.1 million, approximately US$2.8 million showpiece event in Crans Montana.
Lee started the day four shots back of the leaders, but spectacularly birdied eight times in his outward-nine to race up the leaderboard with his birdie blitz only halted by a par on the par-four seventh.
He picked up a further shot at 10th before following up with a par at the 11lth hole.
The Scot looked to be cruising towards that magical 59 until he was setback by a bogey on the 12th.
Lee, however resumed his birdie run by picking up shots on holes 13 and 14 to cap a magnificent round which left many in awe.
“The 59 crept into my head probably as I was coming up the second par five 15th. I was thinking I needed another couple as it was a good chance to make one there. I didn’t know if I was going to find one on the last three as it was a pretty tough finish,” said Lee.
“It was comfortably my best round ever. Even as an amateur or in a bounce game, I’ve never managed to get to double figures. I’ve had some really good ball striking rounds in the last four or five events and some good putting rounds as well, but I’ve never managed to put them together. So this is a nice insight into what can happen."
Denmark’s former Ryder Cup player Thomas Bjorn, who is seeking to win his second European Masters title since 2011, posted a 67 to share second place with Spain’s Alejandro Canizares and France’s Victor Dubuisson on 199.
Thailand’s Thongchai Jaidee emerged as the leading Asian after he battled to a 70 to take a share of 17th place while India’s first round leader Anirban Lahiri could not produce his opening round heroics of 63 as he slumped to a disappointing 75 to stay 12 shots back of Lee in tied-32nd place.
Bjorn was a model of consistency as he only dropped his second shot of the tournament at the par-three 11.
The 2011 Omega European Masters winner offset his bogey with five birdies before following up his successive 66s with a 67.
“It was a very controlled round to be honest. I just tried to stay out of trouble and take a few chances here and there. I succeeded pretty well in that. It was a solid round and I never got ahead of myself. I knew there were always going to be opportunities and I’m happy with the day’s work,” said Bjorn.
Meanwhile after an outward 34, Canizares caught fire on his homeward run with an eagle and three birdies.
“I made birdie on the 10th and from there on, everything just happened the right way. I’m very happy to finish the way I finished although there were a couple of tough putts in the end but I still managed to save the round,” said the Spaniard.
The European Masters is the only tournament on European soil to be jointly sanctioned by the Asian Tour and European Tour and marks the start of the second half of the Asian Tour season.