Austria's Bernd Wiesberger and home favourite Victor Dubuisson set the clubhouse target after two thunderstorms disrupted play in the Alstom Open de France at Le Golf National.
Play was suspended just moments before it was due to get under way at 0730 local time at the 2018 Ryder Cup venue, although the initial delay lasted just 30 minutes.
However, only 42 minutes of play was possible before the threat of lightning again forced players off the course, this time causing a delay of two hours.
After finally making his way to the tenth tee, Wiesberger made a solid start with three straight pars before a birdie on the 13th, and successfully negotiated the daunting closing stretch to reach the turn in 34.
The 29 year old then clicked into top gear on the front nine, carding birdies at the first, third and fifth before dropping his only shot of the day on the par-three eighth by three-putting from long range.
"I played okay," Wiesberger said 4 after carding an opening three under par 68. "I was not driving it great early on and was scrambling round. I had a couple of four or five footers for par but the chances I had I took nicely.
"I had just those two hiccups with the three-putt and not getting up and down from beside the ninth green for birdie, but in general, with the conditions being pretty windy, I was quite happy with that."
Dubuisson had been one over par after five holes, but birdied the 18th after his approach cleared the water in front of the green by just a few feet and also picked up shots on the third, fifth and seventh.
The Ryder Cup star almost found water with his tee shot on the ninth but scrambled a par to the delight of the home crowds.
Germany's Martin Kaymer, who missed the cut in the defence of his US Open title at Chambers Bay and also made an early exit in Munich last week, was a shot off the pace after three birdies and one bogey in his 69.
The morning delays meant defending champion Graeme McDowell only started his bid for an historic hat-trick at 1600 local time.
McDowell successfully defended a title for the first time in his career 12 months ago and would become the first player since Marcel Dallemagne in 1938 to win Continental Europe's oldest Open three times in succession with another victory on Sunday.
The former US Open Champion would also become just the sixth player, after Ian Woosnam, Sir Nick Faldo, Colin Montgomerie, Tiger Woods and Ernie Els, to claim a hat-trick of European Tour titles in the same event.
