Louis van Gaal said Manchester United are still struggling to fill the void left by Luke Shaw, who suffered a sickening knee injury last month.
Left-back Shaw is expected to miss at least six months after suffering a double leg-break in United's Champions League loss at PSV on September 15.
United have tried four different players in the position, though none of Daley blind, Marcos Rojo, Matteo Darmian and Ashley Young have starred at left-back like Shaw.
And while United can return to the top of the Premier League standings with victory at Arsenal on Sunday, Van Gaal conceded his team are still feeling the effects of the England international's absence.
Van Gaal said: "We lost Luke and that is a big blow. I said that this would be the year of Luke Shaw.
"His is the only position which we don't have a double option. So the circumstances are not so good for us.
"Four people have played in that position since Shaw’s injury. And we have won every game, but in my opinion, we don't have a good substitute for Luke Shaw with the same qualities.
"So it's a big blow."
