Ajax coach Erik ten Hag admits negotiations with Manchester United were drawn out.
Ten Hag's move to Old Trafford was announced on Thursday.
He told NOS: "Why did it only become official this week and not before? Because we have reached an agreement.
"Reaching a deal isn't just about the manager and Manchester United, Ajax also play a part and everything has to be taken care of.
"How do I feel about possibly joining the biggest club in Europe? It's a big challenge and I'm looking forward to it, but my focus is on Ajax.
"We are in the race for the title and we play a final every week."