the neutral or intense facial expression of a determined and serious sports player
As soon as the team hit the floor, they put on their game faces.
But you know, the real thing about Mike is he is always going to keep his game face on.
The determined face one adopts in a contest; a mask of hardihood: Just keep your game face. We've come this far/ The advancing Knicks needed to wear their game faces in a hurry, and they did (1980s+)