MOOSIC, Pa.— Luis Severino’s lightning-fast ride up the Yankees’ farm system moved to PNC Field Sunday and when he opened his Triple-A debut with a three-pitch strikeout, his fastball hitting 94, 96 and 95 mph, it seemed he might be headed to the majors by the second inning.

Instead, the 21-year-old showed why the Yankees are so excited about him and that he also still has some growing to do.

Severino ended up needing 91 pitches to get through 4¹/₃ innings in Scranton/Wilkes-Barre’s 7-2 loss to Norfolk, striking out three and giving up two runs.

Still, he stayed on the mound long enough to win over some more fans.

“He has the most live fastball of any starter I’ve seen this season,” said Austin Romine, who caught Severino for the first time since spring training. “There were times he put guys away with it and it wasn’t even close.”

But as the Yankees know — and Severino will find out — he’ll need more than a mid-90s fastball to fulfill the promise the team sees in him.

“His fastball is so electric, he got away with some stuff he won’t get away with up there,” Romine said of Severino.

Against Norfolk, Severino consistently threw 93-95 mph, but his changeup lacked its customary control and his slider still looked like the work in progress that it is. He left some pitches up that hurt him and walked three batters.

One American League scout who watched him for the first time said he liked what he saw.

“When you have that much life in your arm, it’s a great sign,” he said. “I didn’t expect a finished product and that’s not what he is. But that arm is special. Now he has to learn to do the other things.”

And he’ll be learning at a pretty high level.

The Yankees’ other top pitching prospect in Scranton, Bryan Mitchell, marveled at how far Severino has come.

“I feel like he’s got a lot of pressure on him,” Mitchell said. “When I was 21, I was in [Class-A] Charleston. He’s succeeded wherever he’s been, so he deserves to be here.”

Mitchell, 24, had never seen him pitch.

“His arm is definitely live,” Mitchell said. “With that velocity, he can overpower guys. That stuff is going to play anywhere.”

The Yankees will find out if that’s true.

“I think I did good,” Severino said. “The first couple innings I struggled with the [strike] zone.”

So don’t expect the right-hander to ride to the rescue in the Bronx anytime soon.

Severino said he was unaffected by his rise through the organization and accompanying expectations.

“It’s the same baseball,” Severino said when asked if he felt added pressure. “I don’t think about what people say. I just keep working.”

And Romine believes he’ll prove to be worth the hype.

“He’s going to be good,” Romine said. “He’s got them by the throat at 21.”