Despite driving rain at Crans-sur-Sierre, Quesne produced a Gallic masterclass, with seven birdies and an eagle carrying the Frenchman to the very top of the leaderboard on nine under par, one shot clear of Danny Willett after the Englishman shot a round of 67.
Quesne said: "I hit so many good shots, and holed a lot of putts. I managed to stay calm, and I took a lot of pleasure from how I played today. I found a lot of greens, and any time you do that you're going to have a good day."
Like BMW International Open Champion Willett, Quesne already has one European Tour title to his name, having triumphed at this year's Open de Andalucia Costa del Sol, but to add to their tally the duo will have to fend off the in-form Scot Paul Lawrie.
Lawrie is looking to run up the same treble as Thomas BjÃƒÂ¶rn, who last year added the Omega European Masters title to his victories at the Commercialbank Qatar Maters presented by Dolphin Energy and the Johnnie Walker Championship at Gleneagles.
Lawrie arrived in Crans Montana on the back of his triumph on home soil last week, and is confident of signing off with another victory before taking a three-week break from competitive action in the build-up to his second Ryder Cup appearance.
He said: "I played lovely again today, hit a lot of good putts "“ not all of them went in, but a fair few did. So I'm very happy with my day's work, despite the weather. There's not a lot you can do the conditions, You've just got to get on with the job in hand. A lot of guys don't like playing in the cold and the wet, but that plays into the hands of people like me who don't mind it."
Marcus Fraser leads the Australasians, consecutive rounds of 68 having him at 6 under and in a share of 4th position, three behind Quesne.
Scott Barr is two shots further back in a share of 13th position, former winner Brett Rumford 27th and six shots from the lead, Michael Campbell and Scott hend 46th and Marcus Both 58th.
For Campbell, who now bases himself a little further down the Rhone Valley, it was just his 4th made cut of the year.
Play was abandoned for the day due to darkness with two groups left out on the course. The second round will resume at 7.45am on Saturday morning, with the third round not scheduled to get underway before 9.25am.
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