First base coach Antoan Richardson was ejected from the game before the Giants came to bat in the bottom of the third inning at Oracle Park in San Francisco.
"I was prepared for this moment," Nakken said. "Never knew if or when it would happen, but (I) was ready to step in when the team needed me to. So yeah I think it means a lot. It's a fun start to the season so far."
The coach said Tuesday night's unplanned action gave her an insight to what it means for players who are not in the starting lineup, but have to be ready for action.
"Now I know exactly how our pinch hitters feel when (Giants bench coach) Kai Correa comes down to the cage and tells them to get ready," Nakken said. "That's just a great feel for me to have to understand what our players go through."
Nakken, 31, is the first woman to ever have a full-time coaching job on a major-league team, and the uniform she wore for the Giants in the 2020 opener was donated to the Baseball Hall of Fame in Cooperstown, New York.
She was a standout softball player at Sacramento State University before she joined the Giants as a baseball operations intern in 2014 and began steadily going up San Francisco's organizational ladder.
Nakken's big night came just days after another historic moment for women in baseball.
Last week, Rachel Balkovec became the first woman to manage an affiliate of a major-league team when she took control of the New York Yankees’ Single-A team, the Tampa Tarpons.
It’s also the second season that Kim Ng has been general manager of the Miami Marlins. She is first woman and only the second Asian American to become a major-league general manager.