The teenage amateur from Sheffield negotiated the scorched East Lothian links like a seasoned professional.
He emerged from the tunnel under the grandstand by the first tee looking every day of his 18 years.
But 18 holes later, this fresh-faced young slip of a lad bore all the hallmarks of a man who belonged in the elite company of an Open Championship field.
His golf was exemplary.
From tee to green he barely put a foot wrong, from the moment he crashed his opening drive down the first fairway to the 66th shot of his round, a bump and run from the back of the 17th green that set up a birdie.
His only moment of weakness came on the final hole, and even then, he was still mature enough to take his medicine when he found a fairway bunker with his tee shot by playing out sideways.
The double bogey was an unfair finish, but after five hours of golf the former Yorkshire Amateur runner-up and British Boys’ champion will not forget, it did not take too much shine off his day.
“It’s disappointing to double bogey the last but it’s one of those things,” smiled Fitzpatrick.
“Otherwise I thoroughly enjoyed the day and 73 is not bad.
“There’s a lot worse places to be. I’d originally booked two weeks off and planned to watch it at home so this is miles better.”
Fitzpatrick said in the build-up that he wanted to enjoy every moment and he was true to his word, revelling in the occasion and the acclaim.
Cheering him every step of the way was a strong presence from Sheffield.
Around 50 Hallamshire members followed their young star north of the border.
“He’s not just a wonderful golfer,” said one elderly Hallamshire member, “he’s a wonderful young man.”
Fitzpatrick was accompanied onto the first tee by the kind of roar reserved generally for major winners, such was his following.
When he rattled in his first birdie on the second, saved par with a long putt on the eighth and then birdied the 17th, the cheer that greeted each induced a beaming smile from the young man.
He had a word of thanks and a nod of appreciation to the many who offered him words of encouragement.
Fitzpatrick let it all wash over him and was visibly lifted.
“The first tee was a highlight – as I walked through and the crowd erupted,” said Fitzpatrick. “If I hit a bad shot they picked me back up quickly and they were always cheering for a good shot. I got going on the front nine but then started to struggle on the back nine but when I holed from 12 foot for par on the eighth, the crowd went crazy.
“It’s a great feeling. It’s great to look around and see familiar faces, that meant a lot.”
As well as the Hallamshire crew and his family and friends, Fitzpatrick was supported by members of the Yorkshire Amateur team he represents, who had driven up on Wednesday night and camped out to see their colleague pit his wits against one of the most revered courses on the Open rota.
Where many of the top players struggled, Fitzpatrick plotted his way around the course in a manner reminiscent of the veterans who stole the limelight on day one; former champions like Mark O’Meara and Tom Lehman.
He barely missed a fairway, which is fortunate since the rough is so high it would have been up to the waist on this young man of the Steel City.
And on bone-hard greens, he judged the pace and the weight consistently well.
“The birdie on the second helped, and I had a lot of chances on the front nine, I played a lot of good shots into the green,” he reflected.
“I tightened up maybe a little on the back nine, probably due to inexperience. But it was a learning curve and hopefully I’ll do better (today). Hopefully the silver medal is in reach.”
The silver medal goes to the leading amateur, a prize Fitzpatrick will have within his sights if he continues in this vein. Were he to win that, he will surely no longer be a victim of mistaken identity.
“At the start of the week I went into the locker room and someone asked to see my ID, so I had to show him my (player’s) badge and he had to say sorry,” he laughed.
“But it was a bit better (yesterday) although someone asked me for my pass this morning on the range.”
Whatever happens today or in the weekend beyond, Fitzpatrick seems determined to continue on the path he has chosen.
He starts a four-year golf scholarship at Northwestern University – the same college which former world No 1 and Ryder Cup star Luke Donald attended – from September, and is unlikely to rush into the professional game.
He said he felt more nervous on the first tee yesterday than he had two months ago when he was sitting his A-level exams, but continuing his education – golfing and academic – is uppermost in his thinking.
Today he plans to continue plotting his way around Muirfield and will not go “chasing flags” unless the opportunity presents itself.
But whatever happens today, he will always have memories of day one of the Open, and his nerveless exhibition of golf, to recall.
“It definitely lived up to expectations, if not better,” he said. “It was a great day.
“A few people have said that I looked like I belonged and that’s fantastic to hear.
“Hopefully that will come true but I’ve got four years to do at university before that.”