નવ્વાણુંનો ધક્કો.

navvāṇuṁnō dhakkō.

Literally: The blow of ninety-nine.
What it means: Experiencing a sudden setback or failure just when one is on the verge of complete success.

The same thought elsewhere

ગુજરાતી કહેવતસંગ્રહ (Gujarati Kahevat Sangrah) (1923) બૃહદ કહેવત કથાસાગર (Bruhad Kahevat Kathasagar) (1920) · read from the scan by machine — the Gujarati itself is unchecked · English is machine-made and nobody has checked it yet

Heard it differently, or know we've got the sense wrong? Tell us — that is exactly the kind of correction this needs.