NEW YORK -- Never. Not when he was a kid growing up in the Dominican Republic. Not when he became a pro in the New York Yankees' minor league system. Never.

Luis Severino says he has never started a playoff game.

At any level. Anywhere. Never.

Still, he is not sweating his first win-or-go-home start Tuesday night in the American League wild-card game against the Minnesota Twins.

"It's the same game," Severino, 23, said with a big belly laugh, seemingly unworried and unfazed as he stood in front of his locker. "I just have to go out there and have fun."

Severino has done a lot in 2017, moving from a career crossroads to becoming the Yankees' ace. A year ago, Severino regressed, with demotions to Triple-A and to the bullpen. If he didn't perform this season, the Yankees might have made him a full-time reliever. He credits his improvement,which has meant more precision with his fastball/slider/changeup combo, to his work with Hall of Famer Pedro Martinez in the Dominican last winter.

"He told me that if I change my mechanics a little bit, I'll be more consistent in my strike zone," Severino said. "That's what I did, and that's how that worked out and helped me."

In the regular season, the right-hander with a 100 mph fastball went 14-6 with a 2.98 ERA. That won't win him a Cy Young Award, but he very well could place in the top three in voting. And if he's the Severino of the regular season, opposing Twins starter Ervin Santana will have a tough time going pitch-for-pitch with him.

"Hopefully, he is mentally tough enough to do the exact same thing," said Al Leiter, an analyst for the YES and MLB networks who appeared in 21 postseason games and won two rings during parts of 19 seasons in the big leagues. "That is the separator. You don't rise to the occasion. You just continue to do what you've been doing.

"If your ERA is a 2.8, pitch like a 2.8 in the postseason and you are a stud. Don't have your 2.8 become a 3.5. Everyone is bananas, the bunting is up, that all goes into the mind, 'Gulp, don't mess this one up.' Does that affect your performance? It could. He hasn't done it yet so we don't know, but stuff-wise, he can dominate."

Of the Baby Bombers, Severino has always been the most important of the bunch. The Yankees have been trying and failing to grow an elite starter since a kid named Andy Pettitte rose to prominence in the mid-1990s.

From Phil Hughes to Joba Chamberlain to Ivan Nova, the Yankees have had limited success developing starters, but none of them became an ace or good enough to be trusted in a big game. That's why Severino's development has always been a big deal -- even bigger than the development of Aaron Judge or Gary Sanchez.

Tuesday night is the next step in a process that has had Space Mountain-type dips for Severino. Last year's failures made him hungrier.

"He's had a little roller-coaster ride there," Yankees backup catcher Austin Romine said. "I saw a change in his focus. You could tell he really wanted it."

What is really amazing about Severino is his ability to pump his fastball from the first to the seventh inning. He often touches 100 on the speed gun late in games.

Said Leiter: "Stud."

Another starter with big-game experience, CC Sabathia, downplayed Severino's lack of playoff experience. For Sabathia, the fact that the Yankees play so many big regular-season games, especially against the Red Sox, it should be an easier transition for Severino.

"It helps us that we play the Red Sox so many times a year," Sabathia said. "That could be a big game in April. It could be a big game in June. All those games count. All those games feel the same, so that helps us."

Sabathia is the leader of the staff. He could get in Severino's ear to remind him to just keep it simple.

"Just be yourself," Sabathia said he'd advise Severino. "Don't try to do anything extra. Go out and do what you've always done and keep us close in the game and let the team do the rest."

If Severino does struggle, Yankees manager Joe Girardi will have a pretty quick hook, as Chad Green, Dellin Betances and Aroldis Chapman could be called on for multiple innings in the do-or-die game.

Severino has the stuff to escape trouble -- especially his ability to strike out opponents -- so, even if the Twins put some runners on, he still could be Girardi's best option to get out of it.

On Tuesday night, Severino will use his talent to combat his inexperience. It has worked pretty well so far.