dead on one's feet

dead on one's feet  {adv. phr.},  {informal}

Смертельно уставший, но все еще стоящий на ногах или выполняющий работу.

Jimmy never leaves a job unfinished. He continues to work even when he's dead on his feet.

After the soldiers march all night, they are dead on their feet.

Ср: DEAD TIRED, WEAR OUT (2).