CARNOUSTIE, Scotland — Jordan Spieth had no idea how it was going to hit him emotionally.

A year removed from achieving one of his greatest career feats, Spieth experienced one of his most melancholy moments Monday at Carnoustie when he returned the Claret Jug to the Royal & Ancient officials upon his arrival to the venerable British Open venue.

“It wasn’t an enjoyable experience, but it’s done,’’ Spieth said. “I took it to all the places that allowed me to get to where I am today — so my family had it for awhile and so did my team. It’s the coolest trophy the sport has to offer. So having to return it was difficult. Hopefully it’s only out of my possession for a week, which would be ideal.’’

As Spieth readies to defend his British Open title this week, memories of his incredible victory last year at Royal Birkdale have come flooding back.

It wasn’t until the day after one of the most remarkable events of his life that Spieth truly realized what had happened on the Birkdale back nine in the final round.

“I actually watched it the next day,’’ Spieth said. “I got home to Dallas the next day, and I couldn’t help but turn on the final round. [I] fast-forward until the tee shot on 13. I didn’t watch the first 12 holes.’’

Why would he?

What occurred on No. 13 — after his errant tee shot sailed some 60 yards off line — so far over the back side of the dunes to the right of the fairway there was a massive search-and-rescue for his ball before it finally was located.

Upon contact off his driver on 13 Spieth knew. He put both hands on his head as if to say — without words — “What have I just done?’’

He started the round with a three-shot lead and the lead was gone by the fourth hole. After gathering himself, he and Matt Kuchar were tied for the lead on the 13th tee. And then it looked like it was all thrown away — not unlike the 2016 Masters where he famously lost the five-shot lead he held with nine holes to play.

“I was like, ‘I don’t even know exactly what happened on that tee shot,’ ’’ Spieth said of his rewind moment the day after he gathered himself following the calamity on 13. “And then from there, about five minutes into the looking for the ball, I got pretty annoyed with it because it was a lot longer [on TV] than I remember. For me, it went by pretty quickly because it was, ‘OK, decision here, decision here, now I need to drop here …’”

Ah yes, the drop. Perhaps the most famous drop in major championship history — a drop that defined the outcome of that Open, Spieth’s third career major championship.

Spieth, now with chaos added to the inherent stress that already comes with being in contention on the Sunday of a major, had the wherewithal to ask a rules official if he could take an unplayable lie and take a penalty drop way back off that dune — hairy with gnarly club-choking fescue grass — in the practice range near where the equipment trucks were parked, where the grass was tame and short.

“Is the range out of bounds?’’ Spieth asked a rules official.

After a 20-minute-plus ordeal that felt twice that, Spieth was granted the drop, and proceeded to rip a blind-shot 235-yard 3-iron to just in front of the green. From there, he would get up-and-down from over a pot bunker, burying an 8-foot putt for the most important bogey of his life.

“With the [TV] coverage … it was like, ‘Man, that really did take a long time,’ ’’ Spieth said. “That was kind of tough to watch. It was kind of funny … for me, from the tee shot to the third shot, everything went faster than what it seemed when I was watching it [on TV]. But then, after the 13th hole, everything went slower to me than what it [seemed] on TV.’’

Spieth, trailing Kuchar by one shot, followed the tournament-saving bogey on 13 by nearly acing the par-3 14th hole with a pure 6-iron and settling for a kick-in birdie that showed he was back in control.

“I was like, ‘Wow, I kind of stepped up and hit that shot [on the 14th hole],’ but for me it was this whole regrouping and re-motivating and resetting a goal, and all that kind of took place pretty quickly, I guess, in real time,’’ Spieth said. “Watching it on TV, on 14 I looked like a different person, different demeanor, everything. It was kind of weird.’’

Spieth would eagle the par-5 15th hole, draining a 50-foot bomb, and then birdie 16 and 17 to secure a stress-free walk up the 18th fairway with a three-shot lead and the Claret Jug his to hoist.

How good was Spieth after No. 13?

Kuchar went from leading by one shot to playing Nos. 14, 15, 16 and 17 in 2-under par and lost to Spieth by three shots.

“I kept thinking, ‘I’m in good shape,’ but after each hole, even though I was playing well, I was not in as good a shape as I was before,’’ Kuchar recalled.

Despite a season struggling with consistency — last year’s Open was his most recent win — this week at Carnoustie Spieth will try to become the first player to defend his Open Championship title since Padraig Harrington did it in 2007-2008.

He’s enjoyed the spoils of victory in the months since, and insisted that, despite his down 2018 season to date, he has all confidence he can recreate the magic he produced a year ago.

“I have no doubt in my ability to come back and defend whether form’s on, off or anything indifferent,’’ Spieth said. “It’s been an off-year this year. The results haven’t been up to my own expectations, and it’s been putting the majority of the year. I’m looking to get a little bit of momentum of consistency throughout the game. All you need is a little bit of that kind of belief.’’

Belief is a powerful force — more powerful than any of the 14 clubs in his bag. That resolve is what makes Spieth a favorite to take that cherished Claret Jug back home with him for another year.