Manchester United and rivals Manchester City are level at the top of the Premier League with identical records after five games this season.
Only alphabetical order can separate the two sides, with each of them winning four and drawing one.
Former Arsenal midfielder Robson believes the title race this season will be between the two Manchester sides.
However, he admits City’s defence is still a concern for them, whereas United are faultless.
“I think it will be (a battle between United and City for the title),” he said on ESPN FC.
“I think both sides have great qualities.
“We’ve seen Manchester City going forward with great pace and creativity.
“I think they’ve still got a problem defensively and Manchester United are wearing teams down so that, come the end of the game when the substitutes come on, they can just kill off the teams.
“I don’t think there are too many weaknesses (for United).
“I think they play a high-enough tempo now, they’ve got enough pace in the side, they’ve got enough creativity, they know their game-plan defensively.
“I can’t see a weakness in Manchester United.”
Both sides are in Carabao Cup action on Wednesday with United hosting Burton Albion and City travelling to West Brom (both 8pm).