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 yourself in
become accustomed to the circumstances and conditions of a game or activity; get into a rhythm or pattern of working or performing. British