in the saddle
US /ɪn ðə ˈsæd.əl/
UK /ɪn ðə ˈsæd.əl/

1.
no comando, no controle
in a position of control or responsibility
:
•
After the CEO retired, his successor was quickly in the saddle.
Depois que o CEO se aposentou, seu sucessor rapidamente estava no comando.
•
With the new manager in the saddle, we expect significant changes.
Com o novo gerente no comando, esperamos mudanças significativas.