Rooney scored the only goal of the game to put United 15 points clear of Manchester City at the top of the Premier League table.
The 26-year-old has insisted that he and his teammates still have to do their jobs to ensure that they claim the title at the end of the season.
"We knew the three points was the most important thing today, especially with City dropping three points," Rooney told ESPN. "It was a tough game, but we held on and that was the most important thing.
"We knew that the most important thing was our result. We had to make sure we were right and we got the three points regardless of what happened. It was great that City lost but we had to make that up with the three points.
"We are professionals. We know we're in a great position with nine games to go, 15 points clear. But we're professional footballers, we have to go out week-in week-out and do our jobs. Whether we're top, or second in the league you just have to keep going and try to win the games."
Rooney will now join up with the England squad for the World Cup qualifiers next week.