John Terry's first goal for the club since the opening game of last season proved just enough to claim all three points, although the visitors had to survive a late onslaught from Roy Keane's relegation-haunted side.

Kenwyne Jones passed up two glorious late opportunities to snatch a point after Carlo Cudicini had clawed out Andy Reid's first-half free-kick with the visitors hanging on at the death.

The win maintained Chelsea's title challenge, but Grant later insisted the belief that they could regain their crown has always been there.

He said: "If there is even one in the club who does not believe, he should not be in football.

"I am positive and very optimistic by nature, but if I was in a situation where I did not believe, I would be looking for another job.

"The belief was here maybe from the second week I was here. We have shown there is a reason why we can believe in this.

"We believe, even if sometimes we lose games."

The victory, coupled with the 6-1 midweek demolition of Derby, was the required response after last weekend's FA Cup shock at the hands of Barnsley, and it came as no surprise to the manager.

Grant said: "Chelsea wants to be a big club and sometimes even people from outside need to know Chelsea is a big club.

"When we lose a game, it makes us stronger, it does not make us weaker.

"You saw the response after the Carling Cup and the FA Cup - it was not easy because we were all disappointed.

"But we are not changing our way because we lose a game or because we win a game.

"I am happy with the result, of course. It is not easy to play here. Sunderland are fighting for their lives and they fought very, very well.

"We started the game very well. We scored a goal, we could have scored more, but then in the second half, it was more difficult and Sunderland were very dangerous."

Opposite number Roy Keane was left to reflect upon a second successive home defeat with a mixture of pride and disappointment.

He said: "I am disappointed with the result. It was a sloppy goal we gave away, a needless corner and we never quite recovered.

"As Chelsea have done many times before, they are quite good at set-pieces, good delivery, big strong men attacking the ball.

"But the players' reaction over the 90 minutes, performance-wise, I thought they were brilliant - but we lost the game 1-0.

"We have to play with that intensity and level of commitment to the club.

"But on top of that, what really pleased me today was that when we did win the ball back, we played some good stuff.

"We had chances - over the last few weeks, we have not really been creating chances, but today, we had opportunities.

"I have said many times before, football boils down to what happens in both boxes - Chelsea had a chance, they took it; we had ours and we didn't.

"That's why they are going for titles and European Cups. But it is very rare you lose a game at home and get applauded off the pitch."

Meanwhile, Keane dismissed as "utter nonsense" rumours that Kieran Richardson, Daryl Murphy, Michael Chopra and Anthony Stokes, who were not included in the 16, were missing for disciplinary reasons.