But the striker, who set up Ronaldo's 48th-minute goal last night with a wonderfully-floated cross after Vidic headed an early opener, doesn't believe Liverpool are United's only title rivals now that Chelsea have been revitalised under new manager Guus Hiddink.
"I think if we beat Liverpool we'll probably end their chances of winning the League but there's still Chelsea plugging away," he said. "So we have to keep playing. It won't be won yet.
"If we win we'll be in pole position — actually I think we're in pole position anyway. But I'm not sure it's a title decider, with Chelsea still there."
Rooney is clearly delighted with United's current form. They sit seven points ahead of Chelsea and Liverpool, with a game in hand, and made short shrift of Mourinho's return to England as they progressed to the last eight in Europe too — scoring twice against a Mourinho side for the first time ever.
"We're delighted we're through," said Rooney. "To be honest I didn't even know that fact about Mourinho sides, I wasn't aware of it.
"The game is not about Mourinho, it's about Man United and Inter Milan, and thankfully we got through. I'm not really too bothered who we get in the next round now. Whoever we get we know it will be a difficult game because there are no easy games at this stage of the competition.
"The important thing is we're doing well and winning games and we want that to continue. We will just keep trying to win the games and go as far as we can this season."
Last night's result means United are still on target for an unprecedented Quintuple, having already won the Club World Cup in Japan and the Carling Cup over Tottenham.
They are also the semi-finals of the FA Cup and in strong positions in both the Champions and Premier Leagues but Rooney said: "We don't pay too much attention to the talk of five trophies.
"Obviously you see it written in the papers and said on TV but we try to take each game as it comes. We try to do the best we can and hopefully that will be good enough for us.
"We always try to win every tournament we go into and that's no different now. Thankfully we're still in all competitions but there's still a long way to go in the season.
"We know it's going to be a tough run-in being in so many competitions but this is where the squad comes in."
