The moment he walked out the bullpen door, Jose Berrios understood what Ervin Santana meant. When a starting pitcher goes through his normal routine, methodically preparing to pitch at a fixed time he has known for days, the excitement he feels about the assignment is like a slow boil: genuine, but not overwhelming.

But when you are in the bullpen, ready to hop up and go 100 percent at a moment’s notice?

“You get pumped up. It’s different,” said Berrios, who was reminded of that distinction Friday night, when he pitched the fifth and part of the sixth inning and ultimately earned the win against the Tigers. “I talked to Ervin and told him how I felt, and he said, ‘Yeah, that’s exactly how I felt.’ ”

Berrios consulted Santana because he realizes that his second major league relief appearance will probably be nothing like his first: If Tuesday’s wild-card game requires it, Berrios will follow the All-Star to the mound with a season’s worth of pressure on him.

“I know how much it means. It’s just a matter of being ready,” Berrios said through an interpreter. “Yeah, my adrenaline will probably be pumping really high, but it’s just a game. We have to go and enjoy it.”

Berrios had hoped that his stellar second season — the 23-year-old Puerto Rican is 14-8 this season with a 3.89 ERA and 139 strikeouts in 145⅔ innings — might earn the wild-card start for himself, but he understands why manager Paul Molitor chose Santana, the 13-year veteran who won 16 games and posted a 3.28 ERA. And he suspected, even before Molitor and pitching coach Neil Allen approached him, that he might be called upon to be ready on Tuesday.

“I’ve had a good year, I knew that. I was just wondering, in case I got that game, but we know that Erv is Erv,” Berrios said. “He’s made his name and we respect that. So when I knew when he was going to pitch, because of the year I’ve had, I knew I would have to be ready to come in and win. There’s no second game to pitch.”

It’s a role that Santana served himself a decade ago. In fact, Santana has made more relief appearances in the postseason (six) than during the regular season (three).

Santana’s advice for Berrios: Be yourself.

“He’s a very good pitcher, and he just has to have confidence in his pitches. Don’t think about the situation,” Santana said. “He’s got the pitches to get hitters out.”

He does, but Berrios’ brief major league history includes a trend that he would like to ditch, especially if he’s coming out of the bullpen. Berrios’ worst inning is usually his first; he has a career ERA of 6.28 in the first inning, though it’s only 5.40 this season. It can take him a few minutes to settle in.

But Berrios believes his mentality will be different if he relieves Santana on Tuesday. “As a starter, you can kind of play with your pitches. If you miss, you [adjust]. You go attack again,” Berrios said. “As a reliever, you have to attack the strike zone immediately. There’s less chance for you to pick your spots, and I think that’s the biggest difference.”

Molitor said he’s not particularly worried about Berrios’ first-inning hiccups. “It’s rolling the dice, to some degree,” Molitor said. “You can talk about home-road splits, you can talk about first innings — and you can talk about stuff.”

Berrios has it, and now he has at least a little experience out of the pen, too. He has also got some big-game history, having started the 2012 Appalachian League championship game for Elizabethton (he pitched four innings and gave up four unearned runs in a game E-town won), and in the World Baseball Classic earlier this year.

“It’s about how you control your emotions and how you handle your passion for the game,” Berrios said. Friday’s game “was different, but it was good for me. I came out, saw what it takes. I know what my routine has to be. So when Tuesday comes, I’ll be ready for it.”