After a tepid opening period, Saha's introduction at half-time sparked them into life.

Carlos Tevez was instantly a changed man, and with Saha's strength and pace extending Sunderland's defence more than at any previous stage, space began to appear in the Black Cats half.

"Louis Saha made the obvious difference when he came on," said Ferguson.

"He gives us strength and penetration and he got us the goal.

"I didn't want to start with him but at half-time I thought he was needed.

"He is different from the rest of our players and, for the first time, they looked pretty edgy at the back."

The victory, following on from an equally narrow win over Tottenham last weekend, at least allows United to keep pace with their major rivals.

And, when they visit Everton in a fortnight, Cristiano Ronaldo will be back from suspension, Saha should be fitter after his long absence, Ryan Giggs will probably have recovered from the minor hamstring strain that kept him out of today's encounter and maybe, even, Wayne Rooney will be available as he continues to make progress in his recovery from a broken foot.

"The international break has come at a good time for us," he said. "It will give us a chance to get well prepared for the Everton game because the players we have to come back will make a difference."