'chance upon' definitions:

Definition of 'chance upon'

From: WordNet
verb
Find unexpectedly; "the archeologists chanced upon an old tomb"; "she struck a goldmine"; "The hikers finally struck the main path to the lake" [syn: fall upon, strike, come upon, light upon, chance upon, come across, chance on, happen upon, attain, discover]

Synonyms of 'chance upon'

From: Moby Thesaurus