Brad Foster made his first appearance of the season in last Sunday’s 48-6 defeat to Hull KR but suffered a reoccurrence of the shoulder injury that had kept him sidelined.
Foster was due to see a specialist this week but Morrison was fearful that it could be a season ending injury.
With no dual registration or loan players available, Morrison faces reshuffling his pack once more in a bid to get a full squad on the pitch.
Speaking after last Sunday’s defeat to Hull KR, Morrison said: “It may be a case of our players pulling a card out of the deck and that will be the position that they play and just do their best. We just need to get 17 players on the pitch at the moment.
“We won’t have any dual registration players or loans because their teams won’t want them cup tied.
“We have lost Brad Foster with a shoulder injury. He has just come back from that injury and he has done it again, so he will be off to see the surgeon.”
Dewsbury had spells of pressure against unbeaten Kingstone Press Championship leaders Hull KR last week but struggled to break their opponents down and were restricted to a Keegan Hirst consolation try four minutes from time.
Morrison took positives from the display but knows the Rams must be more ruthless on attack.
He added: “In the first 15 minutes of the second half we dominated field position and they didn’t really get out of their half.
“We got a repeat set but James Glover threw a big cut out pass instead of just starting again and we dropped the ball and gave a penalty away and this led to them scoring a try.
“Three of their tries in the first half came off the back of our errors and penalties and just giving them piggy backs out of their end.”
Newcastle have made a fine start to their League One campaign, winning their opening two fixtures and edged out London Skolars 24-22 last week.
Supporters attending tomorrow’s game should note that only the seated North Stand will be open and admission is £13 adults and £10 concessions (over 65s and under 16s) , while junior season ticket holders of both clubs are entitled to free admission.