He entered in the sixth and had to face both Carlos Gomez and Ryan Braun, who were a combined 6-for-6 at that point. Ramirez got Gomez to fly out to right, walked Scooter Gennett and then struck out Braun.
"He's an incredible talent and has been for a long time," Ramirez said of Braun. "I tried to go right at him and execute the game plan that we'd talked about in the bullpen warming up."
It may have helped the right-hander that the Brewers didn't know him well. Ramirez was added to the Cubs' roster on Thursday.
Did he have butterflies?
"Oh, yeah, especially warming up," Ramirez said. "I felt it once I got on the mound. I kind of looked around and took it all in. I said, 'All right, you're here, everything's magnified a little bit, but it's still the same game, so go out there and pitch.' I was able to keep the nerves in check and go out and compete."
He's been a starter most of his career and is still adjusting to life as a reliever.
"I'm getting used to getting up and getting ready fast," he said. "That was the challenge first off and realizing you don't have to do as much to get ready. You're going to have adrenaline. Just get the ball down right away and get the pitches working and compete."
Starting is in the back of his mind.
"Honestly, if I'm in the big leagues, I'm happy doing whatever they want me to do," Ramirez said.
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.