Devastating news for the Dallas Cowboys ... star offensive lineman Tyron Smith is set to undergo season-ending surgery for a scary neck injury.
Head coach Mike McCarthy made the announcement Friday ... and it's massive -- with some believing this move alone could end Dallas' hopes of a Super Bowl.
Tyron is considered one of the best left tackles in the sport ... and is widely viewed as a future Hall of Famer.
And, with the Cowboys already missing star right tackle La'el Collins due to a hip injury .