Ji-Sung Park scored the only goal of the game against the Gunners at Old Trafford.
Ferguson was impressed with his back four, consisting of Rafael da Silva, Rio Ferdinand, Nemanja Vidic and Patrice Evra.
“We defended very well, the back four were fantastic tonight, absolutely magnificent,” Ferguson told Sky Sports.
“So with that foundation it always gives us a great chance.”
He added: “I think we’re starting to get there. I think our form is improving. And, as I say, with the back four playing like that, if they play like that from now on and give us the consistency, then we’re in with a good chance.”
Ferguson was also full of praise for goalscorer Park.
“His goalscoring record against Arsenal is very good,” he said. “He’s been in fantastic form, the lad.”
“We had to play well. I think in these major games you want to perform and I think we did perform tonight, particularly in the first half,” he added.
“The second half Arsenal came into it a bit. They didn’t make any real chances in the game but they pegged us back a little.
“We should have done better on the counter-attack, which we had some good chances in.”
