Manchester City boss Roberto Mancini says it is important his side went into the international break with a win following a mixed run of results.
City had won one of their previous six matches in all competitions but with a first clean sheet this season to go second in the table.
"It was important to finish before the international break with this victory," Mancini said after his side won 3-0.
"Every game is difficult in this moment but we're happy for a clean sheet."
Since beating QPR 3-1 on 1 September, City had only taken maximum points from one of their three top-flight games.
"Maybe we made some mistakes but I'm happy because our performance in general was really good," Mancini said.
"We are disappointed defensively this season but we are looking strong now. Since the international break we have played well."
Aleksandar Kolarov opened the scoring with an early free-kick and substitute Sergio Aguero made it two with a first-time finish.
James Milner's deflected free-kick sealed the points as City returned to the sort of form that helped them win the league last season.
"We needed the second goal to settle us down," added City assistant boss David Platt. "At 1-0 there is always a risk. In the second half we started to play with a lot of confidence and freedom.
"Whenever we're on the back of a bad result, we always get a reaction from top players and that's what we got.
"We are not stuttering as much as people make out. We have set ourselves in a decent position, we are there or thereabouts.
"If you make a parallel with our first seven games of last season, in terms of goals conceded and points, we are better off."
After seven Premier League games this season, City have 15 points and have conceded eight goals. After seven games in 2011-12, they had 19 points, with 10 goals conceded.
Sunderland boss Martin O'Neill had no arguments with the result.
"We were well beaten by a superior team, I have very little complaint," he said. "My complaint obviously is with us.
"We attacked too infrequently and the second goal was a big moment because it allowed them to go and display all their ability without the concern of conceding a goal.
"They deserved to win. They were much, much better than us."