Hornets striker Bernard Mensah will almost certainly not play again this season as he is set to undergo knee surgery.
Mensah had a scan on Friday to reveal the full extent of the damage and Watford today confirmed he will have surgery next week.
The 19-year-old was playing for loan club Braintree Town against Lincoln City on March 18 when he suffered the injury.
Alan Devonshire, the Conference side's manager, was seething about the challenge after the 2-0 defeat.
"It’s a scandalous tackle and [we're talking about] a young kid’s career. I’m sorry, I’m fuming about it," Devonshire told BBC Essex.
"The football match doesn’t matter to me. We lost a game, that doesn’t matter to me.
"That boy’s career is more important. A tackle like that is horrendous. There is no room for it in football."
Tom Miller, the player who made the challenge, later took to Twitter to insist he didn't intend to injury Mensah and felt his tackle was honest.
"Hope the Braintree lad is fine! I never would intend to hurt anyone," Miller said.
"Braintree's manager needs to get a grip! My tackle was honest!"
Prior to his injury, Mensah had managed two goals in nine appearances for Braintree Town.
The Academy graduate, whose contract expires in 2016, made his Watford first team debut as a 79th minute substitute against Bolton Wanderers on November 23.
- Read Watford's injury news ahead of tonight's game with Blackburn Rovers here.
- Almen Abdi is to return to action tonight. Read more here.