The phrase "huge blow" means that something bad or negative has happened, which can have a significant impact or cause a lot of damage. Full definition
Manchester United «agree # 50m fee» to sign world class playmaker in HUGE blow for Chelsea Manchester United transfer news: # 60m forward announcement TODAY, medical done (caughtoffside.com)
The Citizens will now have to host Arsenal in two weeks time without key men Sergio Aguero and Fernadinho, which will come as huge blow (for them). (justarsenal.com)
Arsenal set to miss out on # 200,000 - a-week star Arsenal dealt huge blow in pursuit of # 72M - rated midfielder, player's new deal set to include # 615M release clause Arsenal braced for double swoop from Premier League rival for # 70M - rated duo (caughtoffside.com)