Tottenham striker Robbie Keane's early effort clipped the bar and Rio Ferdinand booted another Dimitar Berbatov shot off the line before Nani's 30-yard blockbuster flicked off Carlos Tevez and flew in.
"It was probably going in anyway but the touch off Tevez was decisive," he said. "I would give it to him."
Having ruled out any move for a striker before the August 31 transfer deadline, Ferguson must now hope his side can maintain their winning momentum against Roy Keane's Sunderland next week.
"It was our least effective performance so far but in the end we got a win," said the United boss.
"This is not an easy league and there are a lot of games you have to battle through.
"Tottenham are the best team we have played, so this win will give us confidence.
"If there is one club in the country capable of going on a long run it is us. And that is what we are looking for."