The 29-year-old Dutchman sealed a £24m move to Old Trafford in the summer after spending eight years in north London.
The move came after months of speculation over the striker’s future – and the United boss revealed he did not think the forward would end up at Old Trafford.
“I never thought we would get him, until he convinced us that he wouldn’t be signing a new contract at Arsenal,” said Ferguson ahead of Arsenal’s visit to United on Saturday.
“We just started working hard with Arsène Wenger and myself, I phoned him quite a few times, and we eventually came to an agreement.
“If Robin had more than one year left on his contract, we would never have got him.
“It was very amicable with Arsène. He made his case because, first of all, he wanted him to stay without contradiction. There’s no doubt about that and he worked hard to keep him.
“The next stage, once he accepted that he had to let him go, was to make sure we paid him the money. And Arsene has always done a phenomenal job getting top dollar for players.”
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