Matt Wallace set a daunting clubhouse target with a sparkling 63 before play was suspended during round one of the dual ranking Open de Portugal at Morgado Golf Resort.
The Englishman reeled off ten birdies - including five in a row from the 12th - to get to ten under par and open up a one shot lead over nearest challenger Sebastian Heisele of Germany.
American Julian Suri and Englishmen Paul Maddy and Jamie Rutherford are a further three shots back on six under after posting rounds of 67.
As for the four Irishmen in action, West Waterford's Gary Hurley posted a two-under 71 to share 31st with Chris Selfridge tied 44th after a 72 and Michael Hoey 65th after a level par 73.
Ruaidhri McGee was tied for 44th with Selfridge on one-under with 15 holes of his opening round still to complete.
Wallace, who won six Alps Tour events last season to earn his Challenge Tour card, made a strong start on Thursday morning, notching four birdies on the front nine to reach the turn in 32.
The 27-year-old began his back nine in style, making another gain at the long tenth before firing birdies at the 12th, 13th, 14th, 15th and 16th to propel himself to the top of the leaderboard.
Wallace then safely parred his final two holes to head into the clubhouse on ten under.
José-Filipe Lima, who was three under after six holes, was the leading Portuguese player when play was suspended at 3.10pm local time due to thunder and lightning.
Home favourite Ricardo Gouveia completed the morning session alongside Major winner Paul Lawrie of Scotland, with both recording rounds of one under par.
Round one will resume at 8.30 am on Friday.
"It was a fantastic round really. It wasn’t looking great at the start when the rain came in ten minutes before my tee time. Then it stopped just as we got on to the tee, so that was kind of a good omen.
"It was the old cliché. I just took one shot at a time and we had a really good day out there. Everything was working well to be honest. Everything clicked. I made two good par saves on the front nine to keep the momentum going.
"After that every hole was at least a birdie chance, so it was a really good day. It’s been a continuation of a good start to the season. I’ve enjoyed it, I love coming out here and playing and hopefully we can keep this going for the next three days."
"Nine under is a great start, I’m happy with that. I put together a few birdies in a row on the front and the back, which helped.
"It was good to see Matt Wallace going out in front of me and giving me something to chase down. It’s just a bit of friendly rivalry. Seeing him chase up the board there a few groups in front of me was great, it was fun trying to keep up.
"It was a steady round, I had a couple of good putts, but then there were a couple of short putts that didn’t go my way so it could have been better, but I’m happy with that."
Paul Lawrie: “I would say it was solid but unspectacular today. I played nicely, but I just didn’t hole many putts on the greens and I made a couple of mistakes, which didn’t help. But I’ve not played a lot of golf recently, so all in all it wasn’t too bad.
“It was quite windy out there. I thought the conditions were quite difficult, but some of the scoring seems good – ten under par from Matt Wallace this morning is incredible.”
“The end was not what I expected. Over the first nine holes I feel like I was playing well, but there were some bad shots in the back nine, maybe the result of a lack of concentration.
“Those shots cost me a little bit, and I also missed a birdie chance on the last hole. But I'm confident and for tomorrow we have to play the same way, with fewer errors, and the results will appear.
“The wind is very strong, it was not easy to putt and it affected my game a little. But it is the same for everyone and there are scores as low as ten under, which shows that it is possible to play well even in these conditions.”