poker face
US /ˈpoʊkər feɪs/
UK /ˈpoʊkər feɪs/

1.
cara de póquer, rostro inexpresivo
an impassive expression that hides one's true feelings or intentions
:
•
Despite the bad news, she maintained a perfect poker face.
A pesar de las malas noticias, mantuvo una perfecta cara de póquer.
•
He tried to keep a poker face during the negotiation, but I could see his excitement.
Intentó mantener una cara de póquer durante la negociación, pero pude ver su emoción.