Fortune is out with medial ligament damage that he suffered in a Champions League play-off clash with Arsenal two weeks ago.
Mowbray said: “The prognosis at the moment is six to eight weeks and it’s two weeks after the Arsenal game where he was injured in the first half.
“He hasn’t had an operation; it will settle down.
“We were aware of it at the interval but he wanted to stay on and adrenaline gets players through. But after the game, the soreness comes.
“He will go through a period of rehabilitation and will get back to full fitness.”
