SOUTHPORT, England – A piece of mint gum and a check of the weather forecast got Jordan Spieth going in the first round of the 146th British Open.

The two-time major winner got off to a good start in search of the third leg of the career grand slam with a 5-under-par 65 at Royal Birkdale to grab a share of the early lead in the oldest championship in golf. In his first bogey-free round in the Open, Spieth made five birdies.

“Really good start. Everything was strong,” Spieth said. “I give it a nine across the board for everything – tee balls, ball-striking, short game and putting. So things are in check. It's just about keeping it consistent.

“ … I couldn't have done much better today. I missed two greens. I think I missed three, but one of them I was putting from the fringe. So essentially missed two greens today in some 15-mph winds. This course has a lot of crosswinds, so it's tough to judge how far the ball is going to fly depending on what shot you play. So that speaks a lot to the ball-striking of the day.”

On a pleasant day full of sunshine after morning clouds floated away, Spieth was atop the yellow scoreboards with Matt Kuchar and Brooks Koepka, the reigning U.S. Open champion. Koepka is trying to join Bobby Jones (twice), Gene Sarazen, Ben Hogan, Lee Trevino, Tom Watson and Tiger Woods as the only players to win the U.S. Open and British Open in the same season. Koepka holed a short bunker shot for eagle on the 17th and made just one bogey on the ancient links by the Irish Sea.

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Paul Casey and Charl Schwartzel are four-under.

Spieth was well rested and confident when he arrived at this charming seaside village after a three-week break following his second win of the season in the Travelers Championship. While he put in a lot of long hours of practice in Dallas, he also hung out with a couple of Michaels in Cabo – Phelps and Jordan.

Then, it turned out, a missing piece to the puzzle of winning the Claret Jug came on the practice ground ahead of his first round. That’s when his coach, Cameron McCormick, offered him a piece of gum.

“I was 1-under through two, and I thought I better keep it in and it's still in now,” Spieth said. “Payne Stewart used to do it and it served him well.”

A check of the forecast also ignited Spieth. As delightful as Thursday was, it will be equally dreadful on Friday. Steady winds are expected to reach 25 mph, lots of rain is supposed to fall, as will the temperatures.

“I thought today's round was extremely important, as they all are, but given the forecast coming in, I thought you really needed to be in the red today,” Spieth said. “You can certainly make up ground, in a round like tomorrow, and we'll see it happen, but being able to kind of play with shots or play a little more conservatively, you make a bogey, because you don't try to do too much on a day like tomorrow, that's nice and very helpful.

“ … I think experience plays a big role in dealing with conditions at an Open Championship. And I feel like I've got a lot of experience for having played four. Had a chance to win. I've been on good ends of the draw, bad ends of the draw. I'm kind of prepared for the worst, having experienced it before. And understand that I can still make pars that way. You control the ball off the tee, keep your hands dry, and you grind from inside 10 feet or you make a mid-ranger for par, something to keep the momentum going, that's important for tomorrow. Being mentally prepared is key. I think I'm going into it, at least going into it the right way, and we'll see if I hold that together.”

Koepka hadn’t played since he romped at Erin Hills in Wisconsin to win the U.S. Open. In fact he only played one round before arriving in England. But once he got here, he played every day leading up to the championship.

He said he wasn’t concerned “one bit” about the inactivity.

“I've done the same thing for years, so it shouldn't take too long to get back into it. But it was nice to get over here early and just kind of get a feel for the golf course and just kind of play again,” Koepka said. “It's more mental with me, just being mentally recharged and being relaxed.

“ … If I start playing four or five weeks in a row, everything just seems to get nonchalant. It just doesn't ever seem like I'm fully ready to play. If you take some time off and kind of recharge mentally, physically, I feel like I'm in really good shape right now, even with that time off mentally. It's nice to come back. You get excited to play golf. And anytime you're excited, you're extremely focused when you're out here. And it's a major championship, and if you can't get up for that, you might as well go home.”