Following his side's victory over the Black Cats, the Red Devils boss, also buoyed by the return of Nemanja Vidic, has ruled out bringing in reinforcements in the transfer window
The victory, courtesy of goals from Robin van Persie, Tom Cleverley and Wayne Rooney, means they retain their six-point lead over rivals Manchester City in second.
It also means that the Red Devils have won their last five Premier League games, a record that has left the Scotsman adamant that reinforcements in January are unnecessary.
"I will not be bringing anybody in, in January - definitely not," Sir Alex, who has been linked with a move for Arsenal's Theo Walcott, told the Mail on Sunday.
The 70-year-old was also buoyed by the return of Nemanja Vidic, albeit one confined to a second-half substitute appearance, as he extolled the virtues of his captain.
"It will take a bit of time but that is a start. He is a warrior and he is our captain," he added.
"He always battles for you and sticks his head on that ball in the penalty area. That is what he is great at."