Sven-Goran Eriksson continued his 100% winning start as Manchester City boss as they saw off Derby at Eastlands.
Johnson hugs Petrov after his stunning opener at Eastlands
Midfielder Michael Johnson got the only goal of the game - City's first at home since New Year's Day, 227 days ago.
It was a cracker too, the 19-year-old drifting infield, playing a one-two with Elano and curling the ball into the top corner from 20 yards.
Stephen Pearson and Steve Howard were both denied by fine Kasper Schmeichel saves as City held on for the victory.
After a remarkable performance at West Ham four days ago, this was a less convincing display from City, though Eriksson will care little for that with another three points in the bag.
Neither will new chairman Thaksin Shinawatra, the former Thai PM given a rapturous reception by City's success-starved fans prior to kick off.
Having belied the fact that they were a team thrown together at the last minute at Upton Park, City seemed less comfortable on their own turf.
Derby were in no mood to be charitable either, as they sought a first away win in the Premier League since March 2002.
Indeed, they created much the better chances in the first half and could, probably should, have gone in at the break with the advantage.
Howard narrowly failed to latch on to Pearson's inviting left-wing cross, while David Jones volleyed against a post from 20 yards, though it would have been ruled out for handball.
Pearson had the best chance, running clean through on to a Howard pass only to be denied by Schmeichel, racing off his line to save in a manner that would have made his dad proud.
Man City's new chairman Thaksin Shinawatra waves to the crowd
Just before the break, Johnson made Derby pay with a goal of fabulous quality to end City's 780-minute goalless run at Eastlands.
Picking the ball up just inside the Derby half wide on the right, he cut in, played a neat one-two with Elano and masterfully stroked the ball into the top corner from 20 yards with the outside of his right foot.
Buoyed by the goal, City improved. Rolando Bianchi clipped a shot at Stephen Bywater, before Elano and Stephen Ireland both tested the Rams stopper from 20 yards.
At the other end, Howard twice went close to his first Premier League goal, first heading at Schmeichel and then being denied a simple tap-in by a brilliant claim from the young keeper.
City introduced Geovanni for the last 15 minutes and the Brazilian proved a handy outlet down the right, with his electrifying pace causing immediate problems.
A free-kick was deflected wide off Elano before a cross from the right just evaded Ireland eight yards out.
Derby pressed for the final few minutes but Schmeichel and the imperious Micah Richards held firm.
Manchester City boss Sven-Goran Eriksson on the club's young stars:
"People forget there are a lot of good young British players here, they are all doing very well. There are more for the future, too.
"Michael's goal was incredible, really a fantastic finish. We needed it, as Derby were defending very well."
Derby County manager Billy Davies on spending more money:
"We've got to buy more players, like everybody else is doing.
"We understand where we are and we have a lot to do in the transfer market. We acquitted ourselves very well tonight against an expensively-assembled squad.
"We've got a big gap to bridge but we didn't take our chances as you must do at this level and it's cost us."
Man City: Schmeichel, Corluka, Dunne, Richards, Garrido, Ireland, Johnson, Hamann, Petrov (Geovanni 74), Bianchi (Bojinov 78), Elano (Mpenza 89).
Subs Not Used: Hart, Onuoha.
Booked: Petrov, Hamann, Johnson.
Goals: Johnson 43.
Derby: Bywater, Mears, Moore, Davis, Griffin, Jones (Teale 46), Oakley, Todd (McEveley 77), Fagan (Earnshaw 70), Howard, Pearson.
Subs Not Used: Price, Leacock.
Ref: Lee Mason (Lancashire).