Rickie Fowler's wonderful gesture for Jarrod Lyle

Evin Priest
Rickie Fowler's wonderful gesture for Jarrod Lyle

An emotional Jason Day and Rickie Fowler are among the golf stars who put themselves in the mix while playing with heavy hearts on day one at the US PGA Championships in Missouri.

As golf mourned the loss of Australian former US PGA Tour player Jarrod Lyle, who died Wednesday night following a third battle with cancer, Fowler fired a five-under-par 65 at Bellerive Country Club to take the clubhouse lead.

Sporting a yellow shirt in support of close mate Lyle, American world No.9 Fowler mixed six birdies with a bogey

"I was scripted to wear a dark blue shirt, so luckily I had a version of yellowish and I'm happy (I) could support Jarrod," Fowler said.

"It was tough news yesterday and it's been a tough few weeks.

"I was lucky enough to be able to talk to him last Friday; one thing that helped was hearing how he felt."

Rickie Fowler went against his sponsor's script to wear yellow for Jarrod Lyle. Pic: Getty

Day, the 2015 PGA Champion, choked back tears while talking to reporters after firing a 67 that left him sharing second at three under, two shots back of Fowler.

"He's a buddy, but he's not there anymore and he's never going to come back," said Day, who used to live close to Lyle in Orlando, Florida.

"That's the hardest thing ... now, I'm tearing up.

"It's heart breaking; I've known Jarrod for a long time and my thoughts and prayers go out to (Lyle's wife) Briony and the two kids."

In an near-perfect ball-striking display, former world No.1 Day missed only one green in regulation while finding 12 of 14 fairways.

But an uncharacteristically poor display on the greens from the the US PGA Tour's No.1-ranked putter prevented an exceptional round.

Ian Poulter continued to wear a yellow ribbon for Jarrod Lyle. Pic: Getty

The Queenslander smashed a 271-yard second shot into the par-5 17th (his eighth hole) but three-putted for a par.

The 12-time US PGA Tour winner has only bettered Thursday's driving display once, during the 2006 Barracuda Championship.

Day's career-best round for approach play was when he hit all 18 greens during the 2016 Tournament of Champions in Hawaii.

Marc Leishman is next best of the Australians at two under midway through his round, while former world No.1 Adam Scott is a shot back at one under.

Australian club pro Craig Hocknull finished at two-over with a 72, while bigger-name countryman Cameron Smith struggled during a 74.