PORTRUSH, Northern Ireland — If anybody stepped to the first tee at Portrush with a powerful memory, it was Shane Lowry.

He is, after all, the last player to win a British Open at Portrush, in 2019, and he had been anticipating for quite a while the emotions that would engulf him for that first tee shot this week.

“I’ve fought with this round of golf in my head for a few weeks now,’’ Lowry revealed after shooting a 1-under-par 70 to stand three shots off the first-round lead. “I knew it wasn’t going to be easy. The first tee shot wasn’t that easy. I wasn’t feeling very comfortable there. 

“I would put that up there with first tee at the Ryder Cup,’’ Lowry went on. “I was fighting with that all morning this morning. It’s going to be all right for the rest of the week. I just wanted to get my tournament under way. 

“Obviously, I want so much to do well in this tournament. I want so much to give myself a chance on Sunday. You can’t do that without hitting a good first tee shot. I knew I needed to do that. We all know the dangers that first hole can throw at you, so I was happy to get under way.’’

Unlike a number of players, who hit irons off the first tee, Lowry went with driver on the tricky hole that has out-of-bounds on both sides of the fairway.

Shane Lowry of Ireland tees off on the first hole during day one of The 153rd Open Championship at Royal Portrush Golf Club. Getty Images

It’s the hole where Rory McIlroy hit his first tee shot out of bounds on his first shot in 2019 and never recovered.

Lowry sent his ball 241 yards, landing in the rough just to the right of the fairway, setting himself up for a 183-yard second shot that put him on the green en route to a two-putt for par.

“I watched a lot of golf this morning,’’ Lowry said. “You see Paddy [Harrington] hit a good tee shot and he had 2-iron in. So, I was like biggest head in the bag, give it a rip. Thankfully it went straight.’’

Shane Lowry of Ireland walks off the first tee during day one of The 153rd Open Championship at Royal Portrush Golf Club. Getty Images

Lowry, who won that 2019 by an astounding six shots, got a massive ovation from the grandstands surrounding the first tee.

He got another huge greeting on 18 as he was finishing his round and McIlroy, another home-country favorite, was getting his round underway.

“Yeah, I wasn’t expecting 18 to be full with Rory out on the course, (but) the grandstand was full,’’ Lowry said. “Nice reception walking down 18. It was pretty cool. Actually, there’s an extra little bit of pressure on that 5-footer (for par to finish the round). It would have been disappointing to miss that.

Ireland’s Shane Lowry reacts after completing his 1-under par 70 on the 18th green on the opening day of the 153rd Open Championship at Royal Portrush. AFP via Getty Images

“The crowd have been amazing all week. I won the last time here, and I’m trying to use it to my advantage. All day, I felt like I handled myself really well. Crowds were amazing. Everything about this tournament has just been great. 

“I tried to kind of use that as motivation instead of sometimes you can put a bit too much pressure on yourself. I tried to use it in a different way today, and I felt like I did a good job with that.’’

Lowry said he had anxious moments on Wednesday night in anticipation of Thursday’s first round, going for a walk to calm himself down.

“I’d say the boys will tell you I was probably a little bit quiet this morning,’’ he said. “I’m not really myself. I’m happy that round of golf is over with, and I’m looking forward to the rest of the week.’’

Who declines an invitation to play in the Masters? Jacob Skov Olesen, who has a share of the first-round lead at 4-under 67.

Olesen, at age 26, became the first Dane to win the British Amateur last summer and opted to immediately turn pro when he secured his DP World Tour card, which meant he was not eligible to play the Masters last April.

The U.S. Amateur and British Amateur champions get invites to Augusta — but only if they retain their amateur status.

“My age was [a factor] a little bit,’’ Olesen said of his reason to turn pro. “It would have been a different decision if I was 19 at the time. But also, getting out on DP has always been a dream of mine. It’s what I watched all the time growing up — Thomas Bjørn, Anders Hansen, those Danish guys before us.

Jacob Skov Olesen lines up a putt during the first round of the U.S. Open. Reuters

“I had already made the decision before even going to second stage of Q-school that if I got through, it would be a no-brainer to turn pro.’’

Among the metro-area players in the field, Chris Gotterup, the native of Little Silver, N.J., who won the Scottish Open on Sunday, opened with a 1-over 72.

Westchester’s Cameron Young shot a 3-over 74. And Max Greyserman, from Short Hills, N.J., had a rough day with a 7-over 78, though he was 6-over at the turn.

Defending champion Xander Schauffele shot an even-par 71. Rickie Fowler, who’s been struggling this season, shot 2-under.

Defending champion Xander Schauffele, hitting a tee shot on the 17th hole, shot an even-par 71 in the first round of the British Open. Mike Frey-Imagn Images

Ryder Cup captain Keegan Bradley shot 1-over. Bryson DeChambeau shot a 7-over 78.

Aussie Ryan Peake — who drew a lot of attention this week because of his past, serving a five-year jail sentence for assault — had a memorable but rough day, shooting a 6-over-par 78 while grouped with Phil Mickelson, who shot a 1-under 70.

After the round, Peake asked and received a ball and a signed glove from Mickelson as a memento.

“I know everyone is going to look at it and say you take the experience in and stuff like that, but obviously very disappointed with the round,’’ Peake said. “I just got beat up out there. I was like Father Christmas out there. I was just handing out presents to the golf course. Obviously, I’ve still got [Friday] and try and do something to make this cut.’’

Asked if Mickelson gave him any advice during the round, Peake said, “He wasn’t offering me help. I would have known I was in a bad place if he’d come over and started offering me help. We chatted. He’s very friendly.’’

Peake, who like Mickelson is a lefty, said he “grabbed his putter off him a few times and had a little feel of it. That’s the OG — the one from the Masters.’’

Irishman Padraig Harrington, a two-time Open winner and fresh off his U.S. Senior Open victory, had the honor of hitting the first tee shot to begin the Open early Thursday morning.

“I got a little emotional when I was clapped on, and then I calmed down,’’ Harrington said. “I hyped up the tee shot as much as I could, so when I got there, it wasn’t too bad.’’

Harrington birdied the first hole but ended up shooting a 3-over 74 after falling victim to some three-putts.

“It was a tough day on the greens, and it just ate into my game,’’ he said. “I had a horrible day on the greens.’’