Sergio Romo spent the first nine years of his career in a Giants uniform.

As the №3 prospect in the organization, the expectation — at minimum — for outfielder Alex Verdugo is to reach the Major Leagues.

At 20 years old, Verdugo already has a year of Double-A ball under his belt — a year in which he more than held his own. He OPSed .743, hit 13 home runs and struck out less than 13 percent of the time. He received his first invite to Major League Spring Training camp this year.

Verdugo is on his way up.

If or when the time comes that he reaches the Majors, he’ll look back at Spring Training 2017 as one of the most important periods of his development as a professional baseball player. And one of the biggest reasons is Sergio Romo.

“He’s definitely taken me under his wing,” Verdugo said. “It’s really cool. It’s eye-opening and really shows maybe I might not be ready for the big leagues now, but I have all this information from Sergio. I can understand it and process it, and it can help me get to the big leagues.”

Romo and Verdugo met in November while playing for Team Mexico in an exhibition series in preparation for the World Baseball Classic. They became fast friends, their fathers — who accompanied their sons to Japan — becoming faster friends.

“It was one of those things where my dad and his dad were, boom, right at the hip,” Verdugo said. “They met in Japan and got along together. They ended up being like brothers. My dad will (now) call his dad up and say, ‘Hey man, where you at.’”

Alex Verdugo was the Dodgers’ second-round pick in the 2014 First-Year Player Draft.

Verdugo and Romo both had no idea at the time that they’d be playing for the same side come spring. Around the time Romo agreed to a deal with the Dodgers in early February, Verdugo’s lodging plans fell through for Spring Training and he phoned Romo up.

“He was like, ‘Sure thing boss. Don’t worry. I got you. We can get a place by the complex,’” Verdugo recalled.

They’ve been roommates since.

Romo said the bond happened simply — because of heritage. Both are American-born, but Verdugo’s grandfather was born in Mexico and both of Romo’s parents are Mexican.

“Alex Verdugo — good kid,” Romo said. “He really has got a lot of swag, got a lot of confidence. He may be somewhat naïve to certain things, and the only reason I say that is because he maybe hasn’t been taught certain things.

“He’s still trying to find himself. I’d like to, if I can, be one of those guys who sends him in the right direction to find himself quicker.”

Romo is returning a favor, in a sense. When he came up to the big leagues with San Francisco in 2008, Brian Wilson looked after him. Two years later, though, he found his true mentor in veteran pitcher Javier Lopez, who was teammates with Romo up until last season.

“When Javy Lopez came over to the Giants, he was a guy who literally big brothered me,” Romo said. “He put his arm around me. He said, ‘You’re OK here, here and here. And you can improve here, here and here.”

Now Romo is in Lopez’s position and he said he has an open-door policy for all younger Dodgers. Verdugo happened to walk through first.

“There are a lot of blessings and experiences I’ve been given,” Romo said. “I just want to share them with him.”

Romo struck out the side on Thursday in his Cactus League debut as a Dodger.

It helps that Romo is so effervescent. Since reporting to Dodgers camp, he has charmed just about everybody with his persistent positivity, permanent smile and cool manner. There may be a 13-year age difference between Romo and Verdugo, but Verdugo said he’s easy to relate to.

“You could go to the bank with him and it will be the funnest day of your life,” Verdugo said. “He’ll make you laugh. We’ll have times where he’ll start a sentence and or I’ll start a sentence and we’ll both end up finishing the sentence at the same time. We’ll be, ‘Ah what? This is crazy.’”

Beyond that, there’s something very real about Romo — his story, his journey to the Majors. His fastball is one of the slowest in the big leagues. In comparison to most Major Leaguers, he is slight. He wasn’t supposed to be here, he tells Verdugo. But the fact that he is, and for much of his career he has been one of the best relievers in the game, carries a lot of weight.

“I’ve learned a lot from him,” Verdugo said. “He always tells me, ‘Man I wasn’t supposed to be here.’ I was like, ‘What do you mean? You have nine years in the bigs, and he explained it.

“(He said), ‘Bro I was just a little Mexicano who had nothing. I wasn’t a prospect. I fought. I worked and worked and kept trying and I got my opportunity. I took it, ran with it and never looked back.’”

So if or when that opportunity arises for Verdugo, he has his role model. He has Spring Training 2017. And he his motto: Take it, run with it, and never look back.