toss-up
US /ˈtɑːs ʌp/
UK /ˈtɑːs ʌp/

1.
pile ou face, situation incertaine, égalité
a situation in which either of two choices or results is equally possible and it is impossible to predict which will happen
:
•
It's a toss-up whether she'll get the job or not.
C'est un pile ou face de savoir si elle obtiendra le poste ou non.
•
The election is a real toss-up between the two main candidates.
L'élection est un véritable pile ou face entre les deux principaux candidats.