Jose Mourinho’s side have won their opening two matches against West Ham and Swansea 4-0 to sit top of the table.
And City could also make it two victories on the bounce when they host Everton this evening.
But Pearce thinks United have more talent in the defensive third than their rivals.
“Are they going to be good enough defensively to win the league?” Pearce told Sky Sports.
“That is the question from me for Man City.
“Are the back four, or back three plus the goalkeeper going to be good enough to keep enough clean sheets to win them games? That’s the big question.
“I think United are better suited to get over the line, keep clean sheets and score goals.”
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City have added new goalkeeper Ederson to their ranks as well as full-backs Kyle Walker and Benjamin Mendy.
And Pep Guardiola has also been linked with West Brom centre-back Jonny Evans as he looks to bolster his backline.
United have added Victor Lindelof but he has yet to feature in the two wins in the Premier League.
City welcome Everton tonight with the Premier League match getting underway at 8pm.
