United now have a five-point lead at the top of the Premiership.
Ferguson said: “This was a significant day with us extending our advantage.
“The players were fantastic and they never gave up and it was a massive victory at this stage of the season.
“We got a break when their keeper dropped the ball and we scored but after that we were brilliant.”
Ferguson added: “We have played the right way and if we do win the league, we deserve it.”