SAN FRANCISCO—During the later innings of the Oakland Athletics and San Francisco Giants exhibition game last night, Alyssa Nakken, 30, stood at the first base coaching box, becoming the first woman to actively coach on the field in Major League Baseball (MLB) history.

After Monday’s game, Nakken tweeted, “I look calm, but what a rush!”

This spring, newly hired manager Gabe Kapler promoted Nakken from a role in the Giants’ player development department to a coach for the team. This represents the latest prominent step for women in the male dominated sport of baseball. According to Erica Hunzinger of npr.com, as of 2018, 30% of pro-baseball employees are women. Out of all the jobs available in the commissioner’s office, as well as for the 30 MLB teams and their respective farm teams, only 188 are occupied by women.

Like the Giants, the New York Yankees, St Louis Cardinals, and Chicago Cubs also introduced female coaches this year. These teams are all following the lead of the A’s, who had Justine Siegal serve as a guest instructor in their instructional league in 2015.

While Nakken will not be one of the seven coaches suited up in the Giants dugout during the upcoming 60 game regular season, she was able to coach during the exhibitions. Kapler said that in addition to coaching the last few innings on Monday’s game, Nakken will be back coaching first base to start Tuesday’s exhibition game.