off one's game

English

(sports, of a competitor) Playing or competing below one's usual level of performance.
- c. 1910, Ralph Henry Barbour, “The Dub”, in The New Boy at Hilltop and Other Stories:
  One fellow I knew once was off his game the whole first half because some idiot was flying a kite over the field advertising some one's pills.
- 1922, P. G. Wodehouse, “A Woman is only a Woman”, in The Clicking of Cuthbert:
  Then the latter, as every golfer does at times, suddenly went right off his game.
(idiomatic, by extension) Performing in any activity below one's usual level; behaving in an irregular, inept, or awkward manner; feeling unwell.
- 2008 April 2, Tracy Connor, "'Mellow' shark dies," Daily News (New York) (retrieved 9 Sep. 2008):
  Big Bertha, the crowd-pleasing sand tiger shark who survived an astonishing four decades at the New York Aquarium, has died. "She was off her game. She slowed down. She wasn't quite right," said Hans Walters, the animal department supervisor.
- 2008 July 28, Christopher Rocchio, “Aaron McCargo Jr. wins The Next Food Network Star's fourth season”, in Reality TV World, retrieved 9 September 2008:
  Adam found himself answering the viewer's questions while also trying to cook—which threw him off his game.
Antonym: on one's game