Defending champion Sam Burns is one of four players to score a seven-under-par 64, after the first round of play at the Valspar Championship on Thursday.

The world number eight had a busy round on the opening day, with nine birdies and two bogeys. He recovered well after bogey the par-four 16th and reeled off birdies on the final two holes to close out his opening 18 holes.

Following a chaotic weekend at The Players Championship, the Florida weather had a positive effect on the Copperhead course, with Burns reaping the benefits from facilitative greens.

"The greens are really receptive with the rain we’ve gotten last week," he told reporters following his round.

"Yeah, I think the golf course will continue to firm up after we get some sun and wind and I think it’s going to play really well the next few days."

Burns, David Lipsky, Adam Hadwin and Jhonattan Vegas share the lead at Copperhead after the first day of play.

Scott Stallings, Richy Werenski, Davis Riley and Danny Lee are one back at six under, while Justin Thomas, Kramer Hickok and Doc Redman are a further two strokes back.

After missing the cut at TPC Sawgrass, Jason Day opened with a one-under-70, only two weeks after the passing of mother.

Notable names in group at four under include Brooks Koepka, Dustin Johnson, Matt Kuchar and Louis Oosthuizen.

Out of the co-leaders, though, Lipsky was the only one to go bogey-free, opening with a birdie on the par-five first to set the tone on a confident front nine. He closed out the round with four consecutive pars.

The 33-year-old has never won on the PGA Tour and has not won an event since his time on the European Tour in 2018.

Luke List has had a long wait for his first PGA Tour win and that was extended after a two-hour wait before triumphing in a playoff over Will Zalatoris at the Farmers Insurance Open on Saturday.

The 37-year-old American, enjoyed an excellent final round six-under-66, highlighted by four consecutive birdies from the third to the sixth holes, to storm up the leaderboard at Torrey Pines.

But List, in his 206th career start, waited almost two hours after entering the clubhouse as the overnight leaders completed their rounds before facing Zalatoris, who also finished 15-under overall, in an 18th hole playoff.

In fading light, the pair both landed their tee shots within inches of each other in a bunker, with List's third shot placed close to the hole, enabling him to tap in to card a birdie.

Zalatoris pushed his longer birdie putt, which was near-identical to his 18th hole putt for victory that he missed, wide left again to settle the playoff in List's favour.

California-born 25-year-old Zalatoris may have clinched victory on the 18th as List patiently waited and practiced elsewhere, but was agonizingly short and slightly wide after a late fade on his putt.

He carded a final round one-under-71, grouped alongside Jason Day and Aaron Rai, with world number one Jon Rahm also making a late charge.

Day shot into a share of the lead after landing an eagle on the 14th hole but had to settle for joint third alongside Rahm and Cameron Tringale at 14-under-par overall.

The Australian, who had not won a PGA Tour title in 1,364 days, finished with back-to-back bogeys to slip from contention.

Rahm rolled in a clutch 26-foot putt to birdie the 17th to be one shot off the pace but only managed par on the last hole.

Joaquin Niemann, Justin Rose, Pat Perez, Sungjae Im and Rai were next, finishing 13-under overall.

Corey Conners withstood hammering winds to claim a two-stroke lead following the opening round at the US PGA Championship as Brooks Koepka impressed but Rory McIlroy and Dustin Johnson struggled.

Prior to Thursday's first round in South Carolina, Conners' best position after any round of a major was equal sixth through 54 holes at this year's Masters at Augusta.

Conners bettered that at Kiawah Island Golf Resort, where the Canadian defied the wind to set the early pace with a five-under-par 67.

Without a victory since his solitary PGA Tour triumph at the 2019 Texas Open, Conners was almost flawless in gusty conditions, holing six birdies with just one bogey.

Conners' lead marks his third career 18-hole lead/co-lead on the PGA Tour (0-for-two to date) and first at a major. Earlier this season, the 29-year-old was tied for the first-round lead at the Arnold Palmer Invitational and finished third – his best result of the season.

Koepka ended day one in a share of second position alongside Keegan Bradley, Viktor Hovland, Aaron Wise, Sam Horsfield and Cam Davis.

Koepka has been plagued by injuries since winning back-to-back PGA Championships in 2019 and a fourth major title in three years – the American star underwent knee surgery in March before missing the cut at last month's Masters.

But Koepka impressed on Thursday, overcoming a slow start to shoot a three-under-par 69.

Koepka double-bogeyed his opening hole on the back nine, however, the four-time major champion only dropped one shot after that as he tallied six birdies.

He has opened the PGA Championship with a score in the 60s in each of the last six years, the longest such streak at any major in the modern era (since 1934), eclipsing Jack Nicklaus (five – 1972-1976 Masters).

Defending champion Collin Morikawa is a stroke further back alongside the likes of five-time major winner Phil Mickelson.

Big-hitting American and reigning U.S. Open champion Bryson DeChambeau signed for an even-par 72 at the close of the first round, level with Jon Rahm and Justin Rose, while Masters holder Hideki Matsuyama, former world number one Jordan Spieth – eyeing a career Grand Slam – and Xander Schauffele shot 73s.

Jason Day and Patrick Reed were also further down the leaderboard as two-time PGA Championship winner McIlroy and world number one Johnson were powerless in the wind.

McIlroy – seeking a first major trophy since 2014 – recorded a three-over-par 75, which included six bogeys and just three birdies.

Justin Thomas also went three over for the day, while Johnson finished with two double-bogeys and a bogey in a forgettable four-over-par 76 display.