Justine Siegal, a female baseball coach who was the first woman to throw batting practice for a Major League Baseball team, will serve as a guest instructor during the Oakland Athletics' instructional league that begins Sunday at the team's spring-training facility in Mesa, Arizona.

Siegal will assist the A's player development staff both on and off the field during instructs, which run through Oct. 17.

In spring of 2011, Siegal threw batting practice for six major league teams: the A's, Indians, Rays, Cardinals, Astros and Mets.

Siegal became the first woman to coach men's baseball professionally when she served as first-base coach for the Brockton Rox, an independent baseball team, in 2009. She also served as an assistant coach for the baseball team at Springfield College from 2008-10.

Siegal is the head coach and founder of Baseball For All, a national nonprofit organization with a mission to provide meaningful instruction and opportunity in baseball, especially for girls.