(CNN) - He carded a five-under-par 65 to take the clubhouse lead at the PGA Championship on Thursday, but golf wasn't all Rickie Fowler was thinking about during the last major of the season.
Jarrod Lyle, the 36-year-old Australian golfer who died Wednesday of cancer, was also very much on the American's mind.
Fowler, one of the most talented modern players not to have won one of golf's four major tournaments, had intended to wear dark blue during the first round at Bellerive Country Club in Missouri.
But he chose to take to the course in yellow, the same color as a bucket hat often worn by Lyle during his career.
"It was tough news yesterday," an emotional Fowler told reporters. "So definitely happy that we could be here and supporting Jarrod. It's been a tough few weeks, especially talking with guys that were also close with Jarrod."
Lyle's family announced last week that the 36-year-old was ceasing cancer treatment before the father of two "passed away peacefully."
Fowler spoke to Lyle last Friday.
"One thing that did help is hearing kind of from him how he felt," Fowler said. "He sounded like he was in a good spot. Obviously that's not something that's easy to deal with.
"And it's been fun to be thinking about him while we're out there playing, because he would probably be the one to kind of kick you in the butt if you started feeling sad or bad. He would kind of give you a hard time and tell you to man up or something along those lines. Maybe not those same words.
"So it's been enjoyable celebrating his life and we'll continue to do that."
Lyle's fellow Australian Jason Day also paid tribute to his friend, praising his ability to stay positive during his long battle with illness.
"I lived across the street from him when we first started out in Orlando," said Day, who is firmly in contention after a first-round 67.
"He's a good buddy of mine. It's obviously heartbreaking to see. I've known Jarrod for a long time, and obviously my thoughts and prayers go out to Bri and the two kids.
"He battled half his life. And the crazy thing is he was always upbeat and positive. No matter what you did, you could be playing terrible, and if you're playing golf with him, you always walked off the golf course happy.
"For him to first get diagnosed with it when he was 17 years old and then battled three times, it just goes to show how much of a fighter he was inside to be able to keep pushing on even though it is painful to go through the stuff that he went through."
By the end of play, Fowler's compatriot Gary Woodland had replaced him at the top of the leaderboard at six under after a 64.
Woodland is six shots clear of Tiger Woods, who is bidding for a first major title since the 2008 US Open, and two-time PGA Championship winner Rory McIlroy. Both former champions ended the day even par.
World No. 1 Dustin Johnson carded a three-under 67 for the day, placing him in the chasing pack, tied for fifth.
Jordan Spieth is hoping to complete a career grand slam of golf's four most prestigious tournaments but he faces an uphill battle at one over par.