Young, Thompson and Cole share lead in rain-hit RSM Classic
Young capped his round at soggy St. Simons Island, Georgia, with back-to-back birdies at the eighth and ninth, finishing with six birdies in his six-under-par 66.
He managed to stay bogey-free despite finding water at the 12th, promptly responding to the near-miss with birdies at 14, 15 and 16.
"The old chunk hook into the water off the tee with the driver happens here and there," Young said. "Obviously (making) that and making some birdies right after, was proud of that for sure.
"The one on nine to finish the day was nice. It was getting pretty dark, it's just a very flat light, it's hard to read the greens, so to make a nice like seven- or eight-footer there was nice," added Young, who is in search of a first PGA Tour title after six runner-up finishes in his last two seasons.
Start of play was delayed for an hour after overnight rain, and play was halted again after more showers left puddles standing on some greens on the Seaside and Plantation courses, both in use for the event.
Young, Thompson and Cole all shot six-under on the par-72 Plantation Course.
Ricky Barnes and Sweden's Ludvig Aberg carded 67s on the Plantation Course and were joined in the clubhouse on five-under by US veteran Matt Kuchar, who posted a 65 on the par-70 Seaside Course.
Ben Carr, Peter Kuest and Nicholas Lindheim were all five-under when darkness halted play, Carr and Keust with one hole to play and Lindheim with four to go.
Ninety players in the 155-man field will have to complete their rounds on Friday.
Cole said he was pleased with his round in sometimes tough conditions.
"Scored well and kind of stayed somewhat patient, stayed relatively patient with a lot going on, so it was good," said Cole, who has three top-four finishes in his last four starts.