be at a disadvantage
To be in an unfavorable position compared to others. They knew for weeks, but I'm just getting all of this information now—I'm at a disadvantage here. You'll be at a disadvantage playing against a player as skilled as Katie.
put somebody/be at a disadˈvantage
make it/be difficult for somebody to succeed: My lack of experience put me at a disadvantage in comparison with the other candidates for the job.