The phrase "open teammate" refers to a player in a team sport who is not being guarded closely by an opponent and is therefore in a good position to receive a pass or be involved in the game. Full definition
And then the passing ability for a big as the game evolves, the ability for a post player to pass and find open teammates is a premium. (sbnation.com)
Must be a disease when a player gets in or around the 18 yard box they become selfish and force a glory move instead of passing to the wide open teammate. (justarsenal.com)
Dembélé plays with a unique and urgent uncertainty: It looks like he's walking on ice — and then he somehow slips through a crowd of defenders and chips the ball to a wide open teammate on the back post. (theringer.com)