Chris Kirk and Zach Johnson share the lead after 7-under rounds of 63 on a packed leaderboard which sees 40 players within four shots of the lead.
A card wrecking quadruple bogey by World Number Two Jordan Spieth has dominated the headlines at the opening round of the PGA Tour's Sony Open in Hawaii.
The American was four under with two holes to play, but he endured a nightmare on the par-four eighth.
Spieth carded three bogeys and a dramatic quadruple bogey in a 69, while Thomas was four shots off the lead after a 67. Defending champion Justin Thomas salvaged an otherwise pedestrian round with a birdie-birdie-eagle finish for a 67. Thomas, an Alabama alum, won a bet that required Georgia graduate Kevin Kisner to wear a Crimson Tide jersey from the tee box to the green. "I've always kind of felt like as long as there's fairways and green and holes to putt it, then I'm going to be fine".
Koepka, the younger brother of U.S. Open champion Brooks Koepka, was among the morning starters and set the clubhouse target by hitting an eagle and seven birdies in his third tournament of his debut season on the European Tour. "I considered hitting a lob wedge because I had something like 30 yards to the hole into the breeze".More news: S&P, Dow open higher as bank shares rise
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"I came here later than I anticipated -like four or five days later and I had zero expectations on my game", the 41-year-old said. That was first of three straight birdies, and he had ample more opportunities, including a shot that hit the pin on No. 10 and settled 3 feet away. He picked up an unlikely birdie on the 13th from the fairway bunker by making a 25-foot putt, and he made a 20-foot birdie on the next hole. "I just feel like it just fits me".
Spieth played well enough to be right there with them except for a pair of long three-putt bogeys - and that one tee shot. He studied his options. If it hit the trees and dropped out, he would have been closer than the drop and at least had an opening to the putting surface.
Waialae is at sea level - waist-high hedges along the 16th and 17th holes and behind the 11th green are all that separate grass from the beach - with smaller, flatter greens and fairways framed by trees.
At this point, he was lying 4 and was only a few yards away from the second tee, waiting for another group to tee off. He had a look at eagle on the par-five 18th, where he holed a two-footer for birdie.