Troon - American duo Justin Thomas and Patrick Reed reached the top of the leaderboard early in the first round of the 145th Open Championship at Royal Troon on Thursday.
Both players reached the start of the inward nine at four under par, with Texan Reed holing his approach shot for an eagle two at the par-four third.
He then added birdies at the fourth, sixth and seventh to reach the turn in 31, but then had a bogey five at the difficult 10th.
Thomas, making his Open debut, birdied his first four holes as well as the seventh before also bogeying the 10th.
Former Masters champion Bubba Watson joined them at four-under as he made shots at four of the first five holes.
In glorious sunshine but with stiff breezes beginning to come in off the Firth of Clyde, scoring has proven far tougher into the wind on the back nine than on the front nine.
Scottish veteran Colin Montgomerie played the first tee shot of the championship as he went out in the first group of the day at 6:35am local time (07:35 SA time).
The 53-year-old Montgomerie, who came through qualifying to appear in his home Open, found a greenside bunker with his approach to the 367-yard par-four first hole and ended up with a double-bogey six.
However, he birdied five of the next eight holes, including the infamous par-three eighth, known as the Postage Stamp.
But three bogeys on the back nine saw him finish with an even-par 71.