England international Wayne Rooney set United on the way to a resounding 4-0 victory at the Stadium of Light with a 20th-minute opener, his first league goal since October.
Rooney then provided the cross for Louis Saha's second with half an hour gone to leave Ferguson delighted.
He said: "I have said before that strikers do go on little runs like that.
"It is his first goal for six games, but his goals have come in waves.
"When he got his injury (in the opening game against Reading), he was out for a month and since then, he has been gradually getting towards what we have seen of him today."
Rooney's contribution to a victory which was every bit as comfortable as the scoreline suggests was only part of the story as Keane's worst fears became painful reality.
The Portugal international, as well as defender Nemanja Vidic, had long departed for well-earned rests when Saha doubled his tally on the day with an 86th-minute penalty.
Ferguson said: "It was an excellent performance, I thought the passing and movement was excellent.
"The first goal put us in the driving seat because we knew Sunderland were going through a bit of a sticky patch.
"It was a marvellous move for the first goal and after that, we did play well."