when the chips are down
(idiomatic) When the pressure is on; when the situation is urgent or critical
He wasn't a very talented musician but, when the chips were down, he played well.
When the chips are down, you need to make tough decisions.
‘If, however, you do not see eye-to-eye with your investors then their rights - particularly when the chips are down - can become a restriction on the development of your business.’ Source: Internet
‘It is like a family, and when the chips are down, everybody is there and just sort of mucks in,’ she says.’ Source: Internet