at the top of one's game

• on top of one's game

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at the top of one's game

1. (informal) Performing as well as one can.

   Synonym: on one's game

• “be at the top of your game” in Longman Dictionary of Contemporary English, Longman.
• “be at the top of your game”, in Cambridge English Dictionary, Cambridge, Cambridgeshire: Cambridge University Press, 1999–present.
• “at the top of one's game”, in Lexico, Dictionary.com; Oxford University Press, 2019–2022.