After an underwhelming season last term, Berbatov now has seven goals in six games in all competitions of the new campaign including a stunning second, via an overhead kick, against Liverpool.
Related ArticlesFerguson blasts TorresGerrard: Liverpool deserved moreManchester United 3 Liverpool 2Hicks courts Blackstone in bid to retain controlMan Utd v LiverpoolManchester United v Liverpool: as it happenedIn his pre-game programme notes, Ferguson warned Berbatov that the current campaign is a "big season for him" and the club record signing responded in the right manner.
"The second goal was unexpected, a surprise attempt," said Ferguson.
"Not many of those end in the net, we see that time and again, but fortunately it did today.
"We are probably now beginning to see Dimitar believe in himself. There was a lot of criticism of him last season, but it happens when players sign for United for a lot of money and they aren't scoring hat-tricks in every game.
"That's the way of the world with some players who come here, but this season he has started in the right fashion. His training has been good, he was good on the pre-season tour and he has carried it on.
"There has never been any doubt about his quality and we have seen it again today."
Ferguson's well-known desire to beat Liverpool was evident in the build-up to the latest meeting between the old rivals and, following the victory, the veteran manager took delight in the win.
"It was always going to be a test," he said. "The build-up to these games is such that, if one doesn't win, it's a catastrophe. For Liverpool, this is a catastrophe.
"People are now talking about Liverpool not winning and it would be the same if we hadn't. That's the nature of these games."
Having seen his side let leads slip against Fulham and Everton already this season, the Bulgarian was relieved to emerge with three points.
"Obviously, it was going through my mind when it was 2-2," said Berbatov.
"But we showed we have good fighting spirit and are always fighting until the end."