be below par / not be up to par

být lehce nemocný, necítit se dobře, cítit se pod psa, nebýt ve své kůži

Do you mind if we put our meeting off till tomorrow? I'm feeling a bit below par today.(CIDI)

After a sleepless night, I wasn't quite up to par. (CIDI)

His eyesight was below par which disqualified him from being a pilot --; and annoyed him a lot --; but he passed out as a navigator. (BNC)

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