deliver (someone) a knockout blow

Translations
нанести (кому-то) сокрушительный удар
The last piece of evidence delivered him a knockout blow in the case.
Последнее доказательство нанесло ему сокрушительный удар в деле.
Definitions
To defeat someone decisively, often in a competition or argument; originally from boxing, where it means to hit someone so hard that they are knocked out and cannot continue the fight.
Words
blow

noun
удар
deliver

verb
доставлять
knockout

adjective
сногсшибательный