play (oneself) in
To become accustomed to or comfortable with a particular action or situation. Used especially in reference sports and athletes. Primarily heard in UK. The rookie goalkeeper had to enter the game after the starter went out with a hamstring injury, and he just never had a chance to play himself in.
play in something
1. to play a musical instrument in some musical organization. I used to play in a band. I wanted to play in the orchestra but I wasn't good enough.
2. [for someone] to play the action of a game in a particular position or location. Fred played in left field for the rest of the game. I will play in the backfield for the rest of the game.
3. to perform in a specific production. She played in the Broadway production of Major Barbara. Once, I played in The Mikado.