SEA ISLAND, November 8, 2013 (AFP) - McNeill was eight-under with two holes to play when the round was halted, with Briny Baird and Brian Gay sharing the clubhouse lead on seven-under-par 63.
McNeill will be hoping to secure his lead when round one resumes on Friday, with the 38-year-old facing a 20-foot birdie putt at his penultimate hole, the par-four eighth.
McNeill's eight birdies in his first 16 holes included five in a row starting at the par-five 15th.
His birdie at the par-five seventh nudged him in front of Baird and Gay, who were able to complete their rounds despite an early morning fog delay of almost two hours that saw 50 players fail to finish.
Baird, 41, and still seeking a first win on the PGA Tour, had seven birdies in his flawless first round. He hit 16 of 18 greens in regulation and notched his lowest score since 2009.
"If there's such a thing as an easy 63, today was," said Baird, who had surgery on both shoulders in 2012 and missed all of 2013 and is hoping that renewed good health will help him find that elusive tour title in the new-look 2013-14 season.
"I do not feel pain in either shoulder," Baird said. "It's a good feeling."
Baird has five runner-up finishes on his resume, and his nearly $13 million in winnings is the most of any active player without a victory, though he said his near-misses don't bother him too much.
"Does it wear on me? A little bit, but probably not as much as it seems," he said.
Co-leader Gay knows what it's like to wait for a first US PGA Tour title. He nabbed his first at the 2008 Mayakoba Classic in his 292nd career start.
He has since added three more, including the Humana Challenge in La Quinta, California, in 2013.
For Gay, the morning fog delay was a welcome chance to rest up after he made the long trip from last week's tournament in China on Sunday.
"I was super tired," said Gay, who took a nap during the delay. "I felt pretty good when I teed off. I felt like I had more energy."
Gay, one of just three players in the field who also played in last week's WGC HSBC Champions tournament, had eight birdies and one bogey in his 63.
Four players were in the clubhouse on five-under 65 -- former US Open champion Webb Simpson, Kevin Kisner, South Korea's Noh Seung-Yul and Kevin Chappell -- while Robert Garrigus was five-under with five to play.
Leading scores on Thursday in the fog-delayed first round of the USPGA $5.5 million McGladrey Classic (Round halted by darkness, to resume Friday. USA unless noted, par-70):
63 - Briny Baird, Brian Gay
65 - Webb Simpson, Kevin Kisner, Noh Seung-Yul (KOR), Kevin Chappell
66 - Scott Langley, Scott Brown, Chris Kirk, Jonathan Byrd, John Senden (AUS), Camilo Villegas (COL), Will MacKenzie
67 - Heath Slocum, Matt Every, Ted Potter, Boo Weekley, Scott Piercy, Tim Clark (RSA), JJ Henry, Brendon de Jonge (ZIM), Brice Garnett, Stephen Ames (CAN), Brian Harman, Trevor Immelman (RSA), Lee Dong-Hwan (KOR)