With chairman designate Khaldoon Al Mubarak watching from the stands for the first time - the takeover will be finalised on Tuesday - City had far too much class for Harry Redknapp's Pompey side which had won its three previous matches.
But they could have no complaints about their defeat which could have been by an even wider margin such was City's superiority in a totally one-sided contest.
And if this is a glimpse of the future, City can look forward to some exciting times ahead.
The match was effectively over as a spectacle after only 20 minutes by which time City had built a two-goal lead.
Indeed, City could twice have taken the lead before they eventually went ahead in the 13th minute as Robinho and Shaun Wright-Phillips had both been thwarted by great saves from David James.
But the England keeper was finally beaten when Robinho's inch-perfect pass released Jo and the striker waltzed around James to score a goal made entirely in Brazil.
City doubled their advantage when Elano's corner was fumbled by James and central defender Richard Dunne forced the ball home from close range.
Peter Crouch had a couple of decent efforts for Pompey late in the opening half, with Pablo Zabaleta denying the striker on the second occasion with a goalline clearance.
Robinho was finally rewarded for his considerable efforts when he scored City's third goal in the 57th minute after another exquisite build-up involving Stephen Ireland and Jo.
And it got even better for City as Wright- Phillips added a fourth goal midway through the second period after running on to a perfect pass from Ireland and lashing an unstoppable angled shot past James at the near post.
City substitute Ched Evans then heaped further misery on hapless Pompey by adding a fifth goal and his first senior effort for the club.
The young Wales striker was released by a cheeky back-heel from Wright-Phillips and made no mistake with a low shot from eight yards.
And to round off an unforgettable afternoon for City fans, substitute Gelson Fernandes scored a sixth goal, which was also his first for the Eastlands club, after being set up by a left-wing cross from Javier Garrido.