。
We have a good chance of winning.
Literal
Us [subject-が] victory [attributive] prospect [topic-は] sufficiently exist.
見込み ('prospect, likelihood, expectation') is a noun from 見込む ('to expect, anticipate'). The attributive 勝利する ('win') modifies 見込み directly (verb + noun, no linking word). 十分 ('enough, sufficient') here is used adverbially. A confident assertion.