Off-chance
If you do something on the off chance, you think there might be a slight possibility of success
Example: I went into the little supermarket on the off chance that I would find a map
Old dog for a hard road
This expression means that experience is invaluable when one is faced with a difficult task
Example: The case calls for an experienced lawyer, an old dog for a hard road
On the fly
If you do something on the fly, you do it quickly, without thinking much about it, while doing something else
Example: I’m so busy I usually have lunch on the fly
One step ahead
When you are one step ahead of someone else, you manage to achieve something faster than they do, or you have a slight advantage over them
Example: The company is successful because they’re always one step ahead of their competitors
Open secret
A fact that is supposed to be a secret but is actually widely known is called an open secret
Example: It’s an open secret that Paul and Julie are living together
Out of the question
Something which is out of the question is impossible and is therefore not worth discussing
Example: Buying a new car is out of the question – we can’t afford it