[fall back on]
or [fall back upon] v. 1. To retreat to.
Theenemy made a strong attack, and
the soldiers fell back on the fort.
2. To go for help to; turn to in time of
When the big billsfor Mother's hospital care came, Joe was glad he had
money in the bankto fall back on.
If Mr. Jones can't find a job as a
teacher, hecan fall back on his skill as a