off your game

off (one's) game

Unable to perform as well as usual. She never misses that shot. She must be off her game today. Staying up late last night really put me off my game at work.
See also: game, off
Farlex Dictionary of Idioms. © 2022 Farlex, Inc, all rights reserved.

off (or on) your game

playing badly (or well).
See also: game, off
Farlex Partner Idioms Dictionary © Farlex 2017
See also:
References in periodicals archive ?
If you are going to be so off your game, it's important to at least get something.
"I'd be more nervous on that side of things than against Australia or France where if you're slightly off your game you could lose by 30 or 40 points whereas if we're off our game here we could lose our reputations."
"It just showed that you cannot be off your game, or take your foot off the pace for one minute," said Atky.