United won the game at the Emirates Stadium 3-1.
An own goal by Manuel Amunia and goals from Wayne Rooney and Park Ji-sung sealed the win for United while Thomas Vermaelen pulled one back late on for the Gunners.
“It was a great performance by us and I’m really pleased,” he told Sky Sports.
“At this time of year you need to kick on. I think Wednesday’s result (a 3-1 win against Manchester City in the Carling Cup) and performance has galvanised us again and you saw today that we were really ready for the game.
“Counter-attack has always been part of our game, especially away from home. We capitalised on a lot of those opportunities today.
“Arsenal play a lot of good football up to the edge of the box, so if you can win the ball there and counter quickly from there you will have chances against them.”
Ferguson admits he will support Arsenal next weekend when the Gunners face Chelsea at Stamford Bridge.
“It’s always a difficult period and we have handled it over the years,” he said.
“I’m hoping we handle it again, but we need Chelsea to drop points. Arsenal are not out of it either.
“I hope they go to Stamford Bridge next Saturday and batter them. I hope they can get some points off them.”
