"We've completed that deal," said Sir Alex. "All the negotiations are over and he'll join us in January."
The boss added that the move for Lindegaard is very much about forward planning, for the scenario when United's number one Edwin van der Sar, now 40, hangs up his gloves at the end of an illustrious career.
"We've got to prepare for the day when Edwin finally bows out," said the boss. "I think that's the main reason [we've signed Lindegaard now], to protect us for the future."