The Jets lost 2-0 to Adelaide United at Hindmarsh Stadium on Saturday and were down to 10 men when their injury woes began.

Adam Griffiths had a knee problem and his brother Joel suffered a hamstring strain in the first half.

It then got worse when Jason Hoffman suffered a serious knee injury and Jesper Hakansson hobbled off the pitch with a corked thigh after the break.

Newcastle coach Gary van Egmond believes Hoffman's injury is 'season-ending'.

"I feel very disappointed for Jason, not only for the Jets but the Under 20s national team campaign is obviously coming up so he's going to miss that. Any player that succumbs to a long-term injury you never want to see that," he said.

Van Egmond said he'd never been involved in a game where so many injuries had occurred in such a short period of time.

"Especially being so early on, we made two substitutions in the first half and then Jesper just after the break; that made it extremely difficult," he said.

The commencement of the National Youth League couldn't have come at a better time for the Jets who'll be looking for its other squad members to hit the ground running after the weekend's injuries.

"It's good that we do have the Youth League now for the fact that we had Antun Kovacic, Kaz Patafta and Jason Naidovski playing in this so they're getting games so they are not coming in underdone," van Egmond said.

Despite the injuries and the score-line, van Egmond was upbeat about the team's performance against Adelaide United.

"The result was poor but the feeling in the dressing room was one of being quite buoyant for the fact of losing key personnel and still being very competitive and doing very well and obviously the resolve and fighting spirit when we went down to 10," he said.

"Tonight's another game that will go down as a turning point in our season and it will carry on giving us more confidence and belief with the games to come."

Meanwhile Jade North admitted the injuries had been unsettling for the side.

"When you've got four of your key players out it's going to hurt you ... I'm proud of the boys tonight, they put in a top effort with 10 men we could've pinched it," he said.

"Sometimes football is cruel."