We found one dictionary that defines the word up one's game:

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1. up one's game: Wiktionary

Definitions from Wiktionary (up one's game) ▸ verb:  Synonym of step up one's game ▸ Words similar to up one's game ▸ Usage examples for up one's game ▸ Idioms related to up one's game ▸ Wikipedia articles (New!) ▸ Words that often appear near up one's game ▸ Rhymes of up one's game ▸ Invented words related to up one's game