Come knocking on (one's) door verb phrase
To present an opportunity or possibility that soon occurs in the future
I can't believe that a great chance like this comes knocking at my door.
I would travel across the country if a million dollars came knocking at my door suddenly.
be braved to face the challenge or quit chances
Nothing but fortunate chance
If you take a flyer (on something), you take a chance, risk, or gamble on it.
The last opportunity for one to achieve something
A second opportunity
The verb "come" should be conjugated according to its tense.