|The 147th Open Championship - first-round leaderboard|
|-5 K Kisner (US); -4 E Van Rooyen (SA), T Finau (US), Z Lombard (SA); -3 B Stone (SA), R Moore (US), B Steele (US)|
|Selected others: -2 M Southgate (Eng), D Willett (Eng), R McIlroy (NI), J Rahm (Spa), Z Johnson (US), J Thomas (US); -1 R Fowler (US), C Wood (Eng); Level A Sullivan (Eng), E Pepperell (Eng), T Woods (US); +1 J Spieth (US), J Rose (Eng), L Westwood (Eng), T Fleetwood (Eng)Full leaderboard|
Rory McIlroy began his bid for a first major in four years with an opening-round 69 as Tiger Woods finished level par at Carnoustie on his Open return.
Northern Ireland's McIlroy, 29, sunk three birdies to leave him three shots behind leader Kevin Kisner.
American Kisner, 34, carded an eagle and four birdies in a five-under 66.
Woods, at his first Open since 2015, was two under after 12 but ended with a 71, while defending champion Jordan Spieth and Justin Rose are one over.
World number one Dustin Johnson saw his chances harmed by a triple bogey on the par-four 18th to finish with a five-over 76.
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"I am happy with 69 and I am happy with my day's work," said four-time major champion McIlroy, whose last triumph came at the 2014 PGA Championship.
"I think with some of the spots I hit it off the tee I would take it."
McIlroy made birdies on the third, 12th and 13th, with a bogey on the fifth was his only blemish, helping him join England's Matthew Southgate and Danny Willett on two under.
South African pair Erik van Rooyen and Zander Lombard, along with American Tony Finau, are a shot adrift of Kisner after 67s, while Brandon Stone - another South African who won the Scottish Open earlier this week - is a further shot behind.
Woods among later players feeling the breeze
Of the 156 players aiming to win the 147th Open, only 31 managed to finish under par in benign conditions on the east coast of Scotland, on the links dubbed Car-nasty.
On a dry, fast course in warm temperatures, scoring proved to be easier earlier in the day with five of the leading seven players having teed off in the morning as the breeze started to pick up in the afternoon.
Woods, 42, was among the late starters and began by sinking a birdie putt from 10 feet on the first, followed by another birdie on the fourth.
The 14-time major winner's progress was stalled by a bogey on the 10th and, after cancelling that out with a 35-foot birdie putt on the next, dropped more shots on the 13th and 15th.
"I thought I played a pretty solid round," said Woods, who has not won a major since 2008. "The round could certainly have been a little better."
Spieth rues 'missed opportunity'
Spieth, a three-time major champion, is bidding to become the first player to retain the Claret Jug since Ireland's Padraig Harrington a decade ago.
The 24-year-old American was three under after 11, but dropped four shots in the final four holes to finish six shots adrift of Kisner.
"It felt like a missed opportunity. I felt like I was really going well," said the Texan.
"I think I'm certainly in a recoverable situation. I mean, I imagine this is as easy as the course could play."
Spieth is one of seven American players sharing a house of the east coast of Scotland this week - along with Kisner.
Only Kisner and Rickie Fowler, who shot an opening one-under 70, have not won a major among the group, with Spieth, Justin Thomas, Jason Dufner, Zach Johnson and Jimmy Walker having claimed eight between them.
"It's not intimidating at all," said Kisner. "Everybody is just really chill and it's a lot of fun to be around those guys."
Koepka, who won defended his US Open title last month, went out in 41 on the front nine before turning his card around with a back-nine 31.
World number two Thomas finished two under, Reed opened with a four-over 75, while five-time major champion Phil Mickelson shot a 73 and two-time Masters champion Bubba Watson a 75.
Willett coming back from 'dark place'
Yorkshireman Willett, 30, has struggled for form and fitness since his surprise win at the 2016 Masters, dropping towards the foot of the world's top 500 before climbing back up to 320th in recent weeks.
After teeing off in the third group of the day at 06:57 BST he responded with an impressive round containing five birdies.
"I'm pretty hopeful we'll never be in as dark a place as we were," Willett said.
Asked to explain how dark it had been, he added: "Pitch black. It wasn't good for a while but that's kind of the situation we were in. We were fighting and the body was being really uncooperative."
World number three Rose was angry with a photographer after missing a short birdie putt on the sixth and his mood darkened further when a double-bogey seven on the 14th dropped him to two over, but he finished with a birdie on the 18th.
Fellow Englishman Chris Wood finished one under while Andy Sullivan and Eddie Pepperell signed for level-par 71s.
Tommy Fleetwood, US Open runner-up last month, is one over alongside Lee Westwood and Matthew Fitzpatrick with Paul Casey, Ian Poulter and Scotland's Russell Knox a shot further back.
Scottish 19-year-old amateur Sam Locke, who works part-time in 1999 champion Paul Lawrie's Aberdeenshire golf centre, shot 72 on his Open debut with 60-year-old Sandy Lyle, who struck the opening tee shot at 06:35, four over.
Sergio Garcia, the 2017 Masters champion, finished four over with Harrington, the champion the last time the Open was held at Carnoustie in 2007, five over.
BBC golf correspondent Iain Carter
It's definitely the case that the guys who were out in the morning had the better conditions. It was a real grind for Woods and co out very late on; the greens were getting crusty and the breeze was getting up.
I rank Rory McIlroy's round very highly. He's not someone who prospers in fast and firm conditions. He said he would be very bold and go with the driver and try and play aggressively as he possibly could and it's paid dividends. He's out early on Friday and kicking off at two under, he'll love that position.