He has still only featured once this season after failing to make it off the bench at Benfica.
"It is hard because of the number of strikers we have," Ferguson said. "Michael Owen is there, Federico Macheda, Mame Biram Diouf. Danny Welbeck won't be back next week but probably the week after. It is not easy.
"Dimitar has been training terrific. His attitude is spot on. He will get his game time as the season wears on. There is no question about that."