This study investigates how rapid impressions of opponents' faces influence players' wagering decisions in a zero-sum game with hidden information. Participants made risky choices in a simplified poker task while being presented with opponents whose faces correlated with different levels of trustworthiness. The results show that threatening face information had little influence on wagering behavior, but emotionally positive faces led to significantly longer reaction times and more mistakes. These differences were most pronounced around the optimal decision boundary, indicating that face information is predominantly used when making decisions during medium-value gambles. Participants' increased folding rates against emotionally positive opponents suggest they may have believed these opponents had hands of greater value. The findings suggest that the best "poker face" for bluffing may not be neutral but rather one that conveys trustworthiness. This study highlights the importance of rapid impressions in competitive games, especially when players have little or no experience with their opponents.This study investigates how rapid impressions of opponents' faces influence players' wagering decisions in a zero-sum game with hidden information. Participants made risky choices in a simplified poker task while being presented with opponents whose faces correlated with different levels of trustworthiness. The results show that threatening face information had little influence on wagering behavior, but emotionally positive faces led to significantly longer reaction times and more mistakes. These differences were most pronounced around the optimal decision boundary, indicating that face information is predominantly used when making decisions during medium-value gambles. Participants' increased folding rates against emotionally positive opponents suggest they may have believed these opponents had hands of greater value. The findings suggest that the best "poker face" for bluffing may not be neutral but rather one that conveys trustworthiness. This study highlights the importance of rapid impressions in competitive games, especially when players have little or no experience with their opponents.