Byeong Hun An was making so many birdies in the PGA Tour event in Mississippi he worried the storms would cost him momentum.
Even waking up at 4 am to play 25 holes on Friday didn't slow him.
An finished off a 6-under 66 in the morning then birdied four straight holes to start the second round, carrying the former US Amateur champion to another 66 and a two-shot lead when play was halted by darkness.
Best-placed Australian Cameron Percy was at 9 under overall and provisionally sixth after completing 11 holes at the Country Club of Jackson.
"I was on a bit of fire yesterday. I finished with three birdies," An said.
"Was a bit disappointing that they blew the horn because I was especially in good shape and I had two par 5s coming in. Two 66s, that's not bad. It was solid apart from one shot I hit in the water."
Instead of setting up a fifth straight birdie in the second round, An pulled his second into a pond on the par-5 fifth hole and made bogey.
He still shot 31 on the front. He finished two rounds with 13 birdies and was at 12-under 132.
JT Poston, who finished his first round with a 64 to share the 18-hole lead with Tom Hoge, had a 70 and was among those at 134, along with Hoge (70), George McNeill (67) and rookie Scottie Scheffler.
Also among those still on the course when play was suspended, Seamus Power of Ireland was at 8 under.
He and Percy each had seven holes remaining in the second round, which was to resume Saturday morning.
If the weather co-operates, it should be no trouble getting back on schedule, especially with a new PGA Tour policy that reduces the cut to top 65 and ties.
An started out his second round with an 8-foot birdie putt, holed a birdie putt from 18 feet on the next hole, got up-and-down from a bunker on the par-5 third - his lone birdie on the par 5s so far - and made an 8-foot birdie on No. 4.
"If you hit it well and in position I think you'll have plenty of birdie chance because the greens are ... they're not soft but they kind of stop dead, so they don't spin as much or they're not as firm as I thought it would be," he said.
Carlos Ortiz of Mexico and Harris English each shot 71 and were at 8-under 136.
Australia's Cameron Davis sits seven off the pace at 5 under through 10 holes.