Robson claimed Ferguson had previous form for the kind of marking job the Scot asked Welbeck to do on Xabi Alonso last week, for he got Brian McClair to carry out a very similar task on Ronald Koeman in the 1991 Cup Winners' Cup triumph over Barcelona in Rotterdam.
"The boss had not spoken about it at all until the team talk before the game, when he told Brian what he wanted," said Robson.
"He was our centre-forward, but he had to do it.
"We went on to win the game and the boss was proved correct.
"It was the same with Danny. It was a tactical decision, that is all. At big clubs they happen all the time and players have to abide by them.
"I realise the suggestion afterwards is that the boss has run out of patience with Wayne but I don't think that is the case at all.
"Purely and simply, he was trying to find the best way of getting into the next round and, but for one decision by the referee, I am sure it would have worked."