Last year in Toronto, the right-hander said he would dash to right field during batting practice to avoid mingling with any players from the visiting team headed to the batting cages in left.
"I don't want to see you or talk to you before the game, because if I have to put one in your neck -- hopefully it doesn't come to that -- I won't feel as comfortable doing it," he said. "Outside of the stadium, we can chat all you want. In here, sorry.
"If you're a pitcher, we'll be best buds. You won't be facing me. If you're a hitter, I don't care where you're from. It'll be all business in here. I have to explain it a little bit to some of the guys."
The Brewers know that about Villanueva, but he anticipates some razzing regardless.
"It's just the way I am," he said. "I believe in the rule about no camaraderie before the game. I'm all for enforcing that rule 1 million percent. We're competing out there. Don't go behind second base and chat away. We're going to compete. That's how I see it."
He also feels strongly about supporting his fellow Dominicans in the World Baseball Classic.
"The last game, I got two calls from the front desk at my hotel, telling me to keep it down," Villanueva said of the D.R.'s 3-1 win over the U.S. in Miami. "I'm whistling and clapping. I think I was more nervous than those guys there.
"It's definitely exciting. You see the style of baseball, it's nonstop noise from inning one, and that's why you see all those young Latin guys coming up and they're unfazed by the big leagues. You pitch with that type of pressure -- you've got your family, your friends, and there's a lot of garbage being talked. It's definitely a way to prepare for the big stage here."
He is aware that the Dominican Republic may not have as large and loud a following in San Francisco as it did in Miami.
"We all wish we could be there," he said. "We have to take care of business here first."
Carrie Muskat is a reporter for MLB.com. She writes a blog, Muskat Ramblings, and you can follow her on Twitter @CarrieMuskat. This story was not subject to the approval of Major League Baseball or its clubs.