Interim Chelsea boss Rafael Benitez boss watched Fernando Torres return to top form to hand him the first Barclays Premier League victory of his tenure.
The Spain international added two first-half goals to the Champions League double he scored against Nordsjaelland in midweek to end a two-month wait to find the back of the net in the domestic competition.
But more importantly, he demonstrated a confidence - his second came from his first ever Premier League penalty - to leave Benitez purring.
He said: "It's fair to say that we are watching now a Fernando with more confidence and with more belief, and at the same time, the team is the same way.
"I was analysing his movement before and we were adjusting little things. It's a question of confidence and just little different movements. I have said before, if the team plays well and creates chances, Fernando will score goals.''
It took Chelsea just 11 minutes to force their way in front when, after a powerful start which could have put them out of sight, Torres finished off a flowing move to end his league drought.
Sunderland, who had endured a dreadful start during which Sebastian Larsson was fortunate not to be sent off for a tug on Eden Hazard's shirt inside the box, responded well and had worked their way back into the game as the half-time whistle approached.
However, Larsson's ill-advised injury-time challenge on Ramires resulted in a penalty which Torres converted with ease, and when Juan Mata struck for a third time after the Spaniard's shot had come back off the bar four minutes into the second half, the game appeared to be over.
Adam Johnson reduced the deficit with a powerfully-struck 66th-minute drive and Craig Gardner hit the bar at the death, but the points were safe.
Both Hazard and David Luiz chanced their arm from 12 yards in midweek, with the former failing, but Benitez was delighted to see Torres take the responsibility this time around.
He said: "For me, the positive thing is that he had confidence. David has a lot of confidence, but Fernando said, 'Yes, I will take it and I will score'.
"We have three and it depends on the moment. Sometimes you have a player who has more confidence. They decide. They are players and they know how they are on the pitch."
The win took third-placed Chelsea to within seven points of leaders Manchester United, although having played a game more, and was just what they needed ahead of their departure to the FIFA Club World Cup in Japan.
Benitez said: "It's always important to win, but especially if you are going to a tournament like this. Every day in training, we have seen this on the pitch and for the confidence of the team it will be fantastic, not just to win, but to win in the way we have won the last two games, with a lot of security on the pitch.''
Sunderland boss Martin O'Neill saw his side slide into the bottom three, just as they were when he took over a year ago, and Tuesday night's re-arranged home clash with Reading has assumed even greater proportions as he attempts to turn around a run of just two league wins in 23 games.
He said: "Tonight, we have dropped into the bottom three and the game that both Reading and ourselves have in hand, on Tuesday night that's over, so from that viewpoint the league will be level.
"It's a tough fight, though, it's a really tough fight. We got some fantastic results last season and it seemed by mid-February that we had calmly taken ourselves out of the relegation problems.
"I never saw it like that. I thought every game was a fight and it is exactly that now. Every game is a fight for us and we need to, when we have a foothold in games, try to make it count. That's the major point."