Royal Birkdale (CNN) He's been sharing tips on high-performance sport with Olympic swimming legend Michael Phelps and it showed in a golden opening round from Jordan Spieth at Royal Birkdale.

Ice-cool in ice-white pants, the world No. 3 charged to a share of the lead after day one of the 146th British Open.

The Texan, with the bow-legged gait of a cowboy, threaded his way through the breeze and bunkers on England's northwest coast in 65 shots for five under par.

It's all stars and stripes at the top of the leaderboard after round 1. #TheOpen https://t.co/ZBw1iLNgeA pic.twitter.com/v2sjOqQAY3

He ended the day tied with last month's US Open champion Brooks Koepka and fellow American Matt Kuchar. Former Masters champion Charl Schwartzel and England's Paul Casey ended four under.

Spieth's round wasn't perfect -- or at least, he rated it a nine out of 10 -- but the 23-year-old found a way to make it effective.

A "top-five, probably" round in majors, he called it, and "extremely important" given Friday's forecast for spells of heavy rain and strong, gusty wind.

It was also significant given the efforts of top-ranked Dustin Johnson, who strode with the loose-limbed prowl of a panther, but could do no better than one-over 71 in balmy afternoon conditions.

Sticky spot

Spieth's perpetual gum chewing told the story: with a flourish, and he liked the shot; with disdain, and he'd hit a bad one.

His putting wasn't always a match for the dead-eye shooting of his double major season in 2015. Often his palm-down hand gesture would will the ball to slow as it charged holewards.

The longer game, too, was occasionally off kilter, mainly blown about by an early Irish Sea wind, which has permanently bent the Birkdale trees to its ferocious will over the years.

On the 10th, Spieth -- black puffy vest over grey, longsleeve shirt -- pulled his second shot onto a grassy bank left of the green.

A little girl spotted it and handed it to her dad. The father was mortified and ordered her to drop it.

The ball was replaced before Spieth arrived, but recognising a sticky spot he told caddie Michael Greller, "Let's just get out of here with a five."

But he pulled off a miraculous recovery for a tap-in to save his par four and remain three under.

'Red-faced'

From the lofty tee looking down over the 13th, Spieth carved his drive right. "Fore," he bellowed, shocking oblivious passers-by.

The ball found the right rough, and while Spieth was assessing his options at its side, an orange-jacketed marshal, trying to stop the gallery using camera phones, trod on it.

Spieth threw his hands in the air, shook his head and called over the match referee. He was awarded a free drop.

Preparing for his shot, he kept up the perpetual conversation with Greller, a former maths teacher. "Wind 45 degrees off the right? No need to be aggressive here. I like this club, huh?"

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He fired the ball forward with a nine-iron, a beauty onto the green, to gasps and cheers from the crowd. They've taken to the young master over here.

The offending marshal's red face clashed with his jacket, but he told CNN he hadn't seen the ball.

Did Spieth say anything to him? "He heffed and jeffed, as they do. Never mind, he'll get over it. He's on the green now."

He more than got over it, and added further birdies at 14 and 17 either side of a stunning par save from the bunker on 16 -- his "shot of the day" -- for a two-stroke lead over the then clubhouse leader Ian Poulter of England.

"Things are in check. It's just about keeping it consistent," said Spieth, who fueled himself up on a breakfast of eggs, bacon, avocado on toast and orange juice.

His meeting with Phelps, the most decorated Olympian of all time, occurred on a recent vacation to Cabo San Lucas with a crew that also included NBA legend Michael Jordan, former Masters champion Fred Couples and NFL star Dwight Freeney.

Photos: Best Open golf courses The British Open rotates around 10 of the best links golf courses in England, Scotland and Northern Ireland. St. Andrews (pictured) is known as the "Home of Golf" and its Old Course is arguably the game's most hallowed turf. Hide Caption 1 of 22 Photos: Best Open golf courses St. Andrews: Golf has been played over the dunes and linksland of St. Andrews since the 15th Century. The clubhouse of the Royal and Ancient Golf Club stands sentinel over the unique layout which starts and finishes in town. Hide Caption 2 of 22 Photos: Best Open golf courses St. Andrews: There are six courses squeezed onto St. Andrews' links, with the Old Course at their heart. The Road Hole 17th and 18th form an iconic finishing stretch. Hide Caption 3 of 22 Photos: Best Open golf courses St. Andrews: The Old Course is known for its blind drives over seas of gorse, vast greens, and swales, humps and hollows which require imagination and the ability to use the ground to your advantage. Hide Caption 4 of 22 Photos: Best Open golf courses Royal Birkdale: The 2017 Open Championship will take place at Royal Birkdale in Lancashire, northwest England. It has been in existence since 1897 and is easily recognized by its 1930s art-deco clubhouse. Hide Caption 5 of 22 Photos: Best Open golf courses Royal Birkdale: This powerhouse of a links features flat fairways and fair greens with holes framed by towering dunes. Hide Caption 6 of 22 Photos: Best Open golf courses Turnberry: Perhaps best known now for being owned by US President Donald Trump, Turnberry on Scotland's west coast is a spectacular Open venue which underwent a recent revamp. Hide Caption 7 of 22 Photos: Best Open golf courses Turnberry: The Ailsa course occupies a sublime location overlooking the Firth of Clyde with sweeping views to the Ailsa Craig rock and the Isle of Arran. Hide Caption 8 of 22 Photos: Best Open golf courses Royal Troon: The classic old links on Scotland's Ayrshire coast last hosted the Open in 2016 when Henrik Stenson won a famous duel against Phil Mickelson on the final day. Scotland's Colin Montgomerie (pictured) is a Troon native. Hide Caption 9 of 22 Photos: Best Open golf courses Royal Troon: The course is famed for its devilish par-three eighth hole, dubbed the "Postage Stamp." It's only 123 yards long but provides a stiff test in the wind, with deep bunkers and a thin green. Hide Caption 10 of 22 Photos: Best Open golf courses Carnoustie: Northeast of Dundee on Scotland's east coast lies the fearsome links of Carnoustie, known as one of the toughest courses on the Open calendar. Hide Caption 11 of 22 Photos: Best Open golf courses Carnoustie: The Championship course is on many golfers' bucket list and is famed as the venue where Jean Van de Velde paddled in the burn during a final-hole collapse in 1999. Hide Caption 12 of 22 Photos: Best Open golf courses Muirfield: The jewel in the crown of Scotland's "Golf Coast" of East Lothian, Muirfield is a celebrated if controversial Open venue. Hide Caption 13 of 22 Photos: Best Open golf courses Muirfield: The testing track near Gullane has been mired in controversy after the club voted -- at the second attempt -- to admit female members. Hide Caption 14 of 22 Photos: Best Open golf courses Royal Lytham & St. Annes: Nestled in a pocket of duneland surrounded by houses and a railway track, Royal Lytham in northwest England retains a charming links quality. Hide Caption 15 of 22 Photos: Best Open golf courses Royal Lytham & St. Annes: The relatively short course still provides a tough test with 206 bunkers to navigate. South African Ernie Els won the last Open here in 2012. Hide Caption 16 of 22 Photos: Best Open golf courses Royal Liverpool: Out on the Wirral peninsula to the west of Liverpool lies the course commonly known as Hoylake, a venerable old links overlooking the Irish Sea. Hide Caption 17 of 22 Photos: Best Open golf courses Royal Liverpool: Legendary golf scribe Bernard Darwin once wrote: "Hoylake, blown upon by mighty winds, breeder of mighty champions." Tiger Woods and Rory McIlroy have both won the Open here. Hide Caption 18 of 22 Photos: Best Open golf courses Royal St. George's: The furthest south of the Open venues in England, Royal St. George's is a quintessential links overlooking the North Sea in Kent. Hide Caption 19 of 22 Photos: Best Open golf courses Royal St. George's: It is a testing mix of undulating fairways, slick greens and daunting bunkers. Hide Caption 20 of 22 Photos: Best Open golf courses Royal Portrush: Hugging Antrim's north coast, Royal Portrush returns to the Open rotation in 2019, the first time the tournament has been hosted outside England or Scotland since it hosted the 1951 event. Hide Caption 21 of 22 Photos: Best Open golf courses Royal Portrush: The Dunluce course is one of the world's most celebrated links layouts hugging the cliff tops and overlooking the Irish Sea with views to Donegal in the west and Scotland in the east. Hide Caption 22 of 22

Vegas, baby

The powerful Koepka took four weeks off after his breakthrough major win at Erin Hills, hitting Las Vegas. Hard, by all accounts.

But back in the gym and relishing another round of links golf after missing the Open last year, the 27-year-old Floridian eased alongside Spieth at five under courtesy of a holed bunker shot for eagle on the 17th.

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"I love links golf," said Koepka, who cut his pro teeth on the European circuit.

"I just wanted to get back inside the ropes. I wanted to have those juices flowing. It's a major championship, and if you can't get up for that, you might as well go home."

The pair were later joined by Kuchar, who is one of the best current players without a major, and well placed after one round to continue the trend of seven first-time major winners.

He was reminded in his news conference that five of the last six Open champions have been 39 or older.

"Regardless of your age, if you're in this field you have a dream to win the title," said the 39-year-old.

Do you know who you are?

The gentle post-lunch zephyrs couldn't blow away Rory McIlroy's recent malaise.

The Northern Irishman, who won the last of his four majors in 2014, cut a dejected figure early on and was five over through nine, and playing third fiddle to partners Johnson and Schwartzel.

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"I was thinking, geez, here we go again," McIlroy told reporters. "But JP [his caddie, JP Fitzgerald) he reminded me who I was, basically. He said, 'You're Rory McIlroy, what are you doing?'"

McIlroy rallied after turning for home, with three birdies in his last four holes to end alongside Johnson.

Poulter, who was second to Padraig Harrington the last time the Open was at Royal Birkdale in 2008, has missed the last five majors with a foot injury and had to come through qualifying to gain his spot.

But it paid off as he shared fifth with the tie-wearing Justin Thomas, green-glove wearing Charley Hoffman, Spanish Ryder Cup star Rafa Cabrera-Bello, England's Richard Bland and another qualifier Austin Connelly, 20, a Canadian who grew up in Texas and is friends with Spieth.

Defending champion Henrik Stenson ended one under, while Phil Mickelson, whom the Swede beat in that epic duel 12 months ago, finished three over.

Thursday is done. Friday could be brutal at Birkdale.