United coaches Mike Phelan, Brian McClair, Rene Meulensteen are in the frame for the post but Ferguson insists the English champions would be in no rush to name a replacement.
He said: "You take your time with these things, there is no hurry.
"We have got good staff and we will carry on, we've always done that.
"We've never made a quick appointment.
"It's always disappointing to lose good men and he was a good man.
"He was honest and very loyal to me and a good coach.
"He brought a lot of initiatives that we now carry on.
"He has taken a challenge on that people do, if they have that patriotic passion and the nationalist fervour to go and manage their country. He's got that.
"I knew when Portugal came for him that it would be very difficult for us."