Wakefield and England winger Tom Johnstone will be out for at least a month after suffering a succession of head knocks.
Johnstone was concussed in successive games, firstly in their loss to Wigan and again in their Challenge Cup defeat by Catalans Dragons on Saturday.
The 25-year-old has been named in England boss Shaun Wane’s training squad ahead of this year’s World Cup.
“We’re hopeful it’s just going to be four weeks,” boss Chris Chester said.
“Both times he’s not been great in the dressing room.
“He has to go to see a specialist. There is a scan and a test that he has to get done and we’ll be medically led on that.
“It’s disappointing for Tom because he’s started the season really well and he’s obviously in Shaun’s thoughts for the end of the season.”
Johnstone has scored two tries in two Super League appearances for Trinity so far this season but stands to miss their games against St Helens, Hull FC, Catalans and Leeds.
Meanwhile, Chester says the club are “a million miles away” from signing Tonga international Andrew Fifita.
The 31-year-old front rower, who is the twin brother of Trinity prop David, has 18 months left on his contract with NRL side Cronulla Sharks but is currently out of favour.
“We’ve had a couple of discussions over the last couple of days,” Chester said.
“We’re a million miles off at the minute. If it happens, then great, if not we’ll look elsewhere. The budget is there and so is cap space to bring in someone else.
“It would be a big boost to the fans and the club and it would bring the best out in Dave. He will add some great value to this club, both on the field and off it.”