United always aim to be top of the charts at Christmas and the Reds boss labelled next Sunday's visit to Stamford Bridge to take on ailing Chelsea as "massive", "a big, big game for United". But first, the Reds had to get past the Gunners.
"These games are important," stressed the boss. "Arsenal were top of the league and we were in third, so it was an important result for us.
"The game-plan was to stifle the midfield and to make sure we got possession of the ball in there. We did that well in the first half. We played very well and maybe we should have been further in front.
"In fairness, with the goal we did score, we deserved that. In the second half we had some great opportunities on the counter-attack, we were disappointed [not to make more of that]. Arsenal had more of the game in the second half without actually making many chances."
Ji-sung Park's looping head just before half time ensured a lead United's play had warranted. The Reds could have extended the advantage playing on the counterattack in the second 45 minutes when Nani won a penalty for Gael Clichy's handball. However, Rooney blasted the spot-kick over the bar.
"I'm surprised," said the boss. "He usually gets his shots on target. It was the complete opposite to the one he scored against Rangers, which was low, hard and in the corner. Tonight he ballooned it over the bar.
"You always worry at 1-0. It's not a great score in a game like this. It only takes a second to lose one. But I thought our back four were fantastic.