But former United and England captain Robson expects Ferguson to overhaul his squad this summer, whatever the outcome of the title race during the next three weeks.
United will hold only a three-point lead going into next Monday's derby at the Etihad Stadium after losing at Wigan and being held to a 4-4 draw by Everton at the weekend.
Robson told journalists: "If United pip City for the title, Sir Alex will take extra pleasure because it is at the expense of the local rivals.
"There has always been great rivalry between the two clubs but for the first time in many years, City are up there challenging for the title.
"That is why for Sir Alex, with it being Manchester City, it will be extra-special for him, because of the resources City have got.
"They've got a great squad while Sir Alex has brought a few kids through and had a lot of injuries to contend with this season.
"It will be a great achievement if United win the title this season. It will give Sir Alex great satisfaction."
Robson expects City to continue to spend big money on their squad but expects Ferguson to also be busy in the transfer market this summer.
He said: "City can afford to do that (bring in top players) but the one thing Sir Alex will do, whether he wins the title or not, is to build in the summer.
"He will do that to try and compete and get back above, or to stay in front of Man City, depending on what happens during the next three games."
Robson believes the key to the derby clash could be how City handle the kind of pressure United have been accustomed to at this stage of a season for many campaigns.
He said: "It will be a new experience for City and depends on how they adapt to it.
"It might be them saying 'let's get out there, enjoy this and, if we do it, we do it, and if we don't no one is really going to criticise us because United have been there, seen it and done it'.
"The players could get that response or do they go the other way and get nervous because they know how much is on this game?"
Robson feels surrendering the two-goal lead to Everton will hurt United more than the defeat at Wigan a fortnight ago.
He said: "I think sometimes people just get carried away and expect it too easy.
"United had been on an incredible run of 12 wins out of 13 so when they went to Wigan, it is not a shock that they had a bad night. That can happen in a season.
"The real disappointment to everyone at Old Trafford is being 4-2 up and not killing the game off against Everton. That was bad defending and that was a concern."