City head into the derby not only ahead of their local rivals but knowing Sir Alex Ferguson's men cannot overtake them even if they repeat last season's triumph at Eastlands.
Eriksson's men maintained their 100% start to the campaign thanks to Michael Johnson's single strike against newly-promoted Derby.
The goal - City's first in the Premier League on home soil since New Year's Day - took the Blues to the heady heights of second spot, trailing Everton on goal difference.
Rarely have City fans approached a derby in such optimistic mood.
Yet Eriksson is too experienced to be sucked into the belief his side are in for an easy time.
"Sunday is a big one," he observed.
"Of course, they are the champions, so it is a big test for us."
United will head across town without two of their key men in injured striker Wayne Rooney and Cristiano Ronaldo, whose dismissal at Portsmouth means he will sit out the encounter through suspension.
For most City supporters, the absences are a further reason to cheer. Eriksson, though, is less pleased.
"It is a pity," he said. "As a fan or a spectator in front of the TV, you want to see the best players perform.
"But they have so many good footballers I think they can put in another one who is very good as well."
Much has been made of Eriksson's assault on the transfer market.
Having brought eight new players in since succeeding Stuart Pearce last month, the Swede's line-up is almost unrecognisable from the one which ended the season.
However, it was four academy graduates who caught the eye against Derby, as Micah Richards, Stephen Ireland, Kasper Schmeichel and goalscoring hero Johnson led the victory charge.
"It is fantastic to see so many young players doing well," said Eriksson.
"I must congratulate the club's academy for the extremely good work they have done."
England Under-21 international Johnson has forced his way into Eriksson's plans despite playing only nine first-team games prior to Saturday's opener at West Ham.
Now he has his first senior goal as well, along with heaps of praise from a former England coach.
"I saw him on TV last season," said Eriksson. "He is a very fresh boy but for his age he is also very clever.
"He can pass the ball, he can defend and he has a good engine. But above all, he is just a very good player."
Eriksson admitted his team have exceeded his expectations, although the Swede also knows City will face stiffer tests than this one.
Derby were enthusiastic opponents but once Schmeichel denied Stephen Pearson midway through the opening period, they never really looked like forcing a breakthrough.
"We can't compete with the resources of Manchester City, so we have to do our best with the money we have," said Rams boss Billy Davies.
"I don't feel there is enough arrogance about our play at the moment.
"We had a couple of chances but at this level, you have to take them."