Trevor Murphy carded a 6-under 66 on Thursday to grab the lead of the Tour Championship of Canada before play was suspended for darkness.
The start of the first round was delayed 5 hours and 20 minutes due to several thunderstorms in the area.
Trey Denton, Bentley Nakasawa and Johnny DelPrete shot matching 4-under 68s on the Championship Course at Sunningdale Golf & Country Club to share second place.
Nick Taylor, who sits in seventh place on the PGA Tour Canada's Order of Merit, is among a large group of players tied for fifth place at 3-under 69.
The top five players from the Order of Merit at the end of the Tour Championship earn status on the Web.com Tour for next season.
Murphy started on the back nine and opened his birdie-free round with a gain at the 10th.
He would add birdies at Nos. 13, 15 and 18 to make the turn at 4-under. After picking up another birdie at the first, he followed seven straight pars with a birdie at the last to grab the clubhouse lead.
Denton and Nakasawa both countered a pair of bogeys with six birdies during their opening rounds, while DelPrete had an eagle, three birdies and a bogey to move into a share of second.
NOTES: Sixty-six players will need to complete their first round on Friday when play resumes at 8:00 a.m. ET ... Taylor trails Joe Panzeri by $3,652 for fifth place on the Order of Merit ... Panzeri is one of the players who will need to complete his round on Friday morning.