Real Madrid pulled one back with the last effort of the game, a stunning goal from Oscar Rodriguez, but they looked far from themselves as City dominated.
But he did confirm that City were still looking at options in the market, albeit he was coy on whether another striker was on the agenda. He saved many, many balls.
Gabriel Jesus and Sergio Aguero both went close at the other end, but once Otamendi found the net in the 52nd minute, on the rebound after Stones's header was saved, City were rampant.
"We controlled a lot of games last season in the Premier League, maybe 95 per cent of all the games we played".
"Since I arrived I've seen Kevin and when he's in the right mood, optimistic and happy, he makes a performance like this", Guardiola is quoted by The Mirror as saying.
Toure knows what the defender is capable of, but says Manchester City needs him to adapt quickly.
The first half ended scoreless but it had moments of brilliance from players of both teams.
However, City boss Guardiola cautioned against overstating the significance of seeing off the Liga and Champions League holders in a warm-up game.
"We will see. I hope he can adapt as much as possible because we don't have time".
"Real Madrid never play badly". Pre-season for them is not as important as it is for us.
"We have a team that can do it, experienced young players who play very well".
The megabucks side finished a disappointing third place in the Premier League and failed to win a trophy during Guardiola's inaugural season.
The Cityzens are believed to have launched a world record bid for the teenage prospect who is also a Los Blancos target.
De Bruyne joined City from Wolfsburg in 2015 for £55m, just a year after departing Chelsea.
Real Madrid will do battle with Barcelona at Hard Rock Stadium in Miami, while Manchester City will travel to Nissan Stadium in Nashville, Tennessee, for a showdown against Tottenham Hotspur. Whilst it's not a reason to panic, it's clear that Zidane has some work to do prior to this weekend's El Clasico.
"It was not important to them".
I had to have surgery on my nose.
"I've been impressed by the youngsters".