When someone is said to be "playing first fiddle," it means they are in a dominant or leading position. Some antonyms for this phrase include "playing second fiddle," "taking a back seat," "following the lead," "being in a subordinate role," or "being a supporting player." In these contexts, individuals may feel less confident, powerful, or in control than the person "playing first fiddle." However, it's important to remember that every member of a team or group has a valuable role to play, and sometimes stepping back or supporting others can be just as important as taking the lead.