He has confirmed winger Darnell McIntosh is out for the rest of the year after rupturing his Achilles tendon against Hull FC - the club he is reportedly joining in 2022 - on Friday night.
Watson added that Joe Wardle will also miss the rest of the campaign due to injury and there is a fear captain Aidan Sezer and hooker Adam O’Brien may end up in the same situation.
Ahead of tomorrow’s visit of Super League leaders Catalans Dragons, he said: “Darnell’s Achilles has gone so it’s the end of the season for him which is obviously a shame.
“He’s been really good for us. When he’s played on the wing, he’s been outstanding for us, so it is a devastating blow.”
Asked how the 23-year-old is, Watson added: “He’s alright.
“He’s come round to it now and knows it’s part of the game.
“He has to focus on his recovery now and getting himself right for next year.
“He won’t be with us next year so that’s obviously his Huddersfield career finished. It isn’t the way he’d have liked to finish it or us.
“But we have players in the squad who can cover that position.”
Watson confirmed Academy stand-off Will Pryce - son of former Bradford Bulls and Great Britain star Leon Pryce - will make his Giants debut tomorrow as Huddersfield continue to fight a lengthening injury list.
Australian scrum-half Sezer - linked with a return to the NRL or Leeds Rhinos at the end of of the season - injured his ankle when playing for the Combined Nations All Stars against England on Friday while hooker O’Brien dislocated his shoulder recently.
“Aidan is going to be out and, in terms of length, it depends on which way he goes with the consultant,” said Watson.
“It’s whether he tries to rehab it or whether it needs an operation.
“That’s a decision for Aidan now to think about.
“It will be a minimum eight to ten weeks which is a bad blow.
“We have people like Cogs (Jack Cogger), Gasky (Lee Gaskell) is added to that list now, Bruno (Michael Lawrence), Joe Wardle and Adam O’Brien who are all beyond eight weeks.
“Some of those are season-ending. Joe won’t play again this year and Adam O’Brien, if it’s not season-ending, then it’s very, very close to season-ending.
“Hopefully the way he rehabs and heals might get him back but it’ll only be towards the back end of the season.
“We’re doing it tough but there’s some guys within the squad and some younger guys to come in.”