Nick Taylor grabbed a one-stroke lead at the Shriners Hospitals for Children Open as Brooks Koepka made a slow start to his season on Thursday.

Canada's Taylor fired an eight-under 63 in the opening round in Las Vegas to edge into the lead ahead of Brian Harman (64).

Eyes were on world number one Koepka, who is making his first appearance of the 2019-20 PGA Tour season.

The American four-time major champion underwent a procedure on his left knee after the FedEx Cup playoffs and he was below his best in the first round in Nevada.

Koepka endured a rollercoaster round with four bogeys and four birdies through his first 15 holes, before picking up a shot at the last to shoot a one-under 70 and be tied for 85th.

Brooks' younger brother, Chase, fared far better, managing a five-under 66 to be tied for eighth.

Phil Mickelson is among a group of five players who are tied for third at six under.

The American veteran carded a 65 to sit alongside Brian Gay, Sam Ryder, Brian Stuard and Maverick McNealy.

On what is a congested leaderboard, there are 12 players tied for eighth, including defending champion Bryson DeChambeau and Adam Scott.