Rooney faces a two-game domestic ban for swearing into a TV camera after scoring against West Ham United on Saturday but he was the consummate professional in the 1-0 United win at Stamford Bridge.
He sidefooted past Petr Cech after 24 minutes following a perfect pull-back by Ryan Giggs to send United confidently into next Tuesday's return at Old Trafford, where they have been formidable all season.
The goal was the icing on a particularly tasty cake for the England striker, who looked sharp, committed and absolutely up for the job in hand despite the latest off-field distraction.
"His performance was tremendous, he is now scoring more regularly," United manager Sir Alex Ferguson told reporters after the re-run of the 2008 final when his men were also victorious, after penalties.
"Wayne was in tremendous form. Excellent, absolutely superb. (His) work rate, desire to play is marvellous. He got a lot of abuse tonight, he got a lot of late tackles on him but he got up and played.
"It shows the courage of the player. He takes great credit."
Chelsea will feel aggrieved that they are not travelling north level at 1-1 after the Spanish referee Alberto Undiano Mallenco ignored a strong stoppage-time penalty claim when Patrice Evra brought down Ramires.
"Everyone saw what happened - you can see it clearly on the TV - but the most important person (the referee) didn't see it," said Chelsea keeper Cech.
Chelsea should be more concerned with their own frailties, however, as they struggled to impose themselves.
TORRID NIGHT
A scramble late in the first half when Didier Drogba hit a post and Frank Lampard's rebound was cleared off the line was the nearest they came to scoring. Squeezed for space in midfield and around the United box they looked short of ideas.
Fernando Torres endured another torrid night as rarely looked close to breaking his goal drought which now stretches to nine games at his new club.
The desperate Spaniard's final contribution was to get booked for diving in a vain bid to secure a penalty under a challenge from Antonio Valencia.
United had arrived looking for their first win at Stamford Bridge in 10 games stretching back to 2002 but they looked sharper from the off.
Rio Ferdinand was back after an 11-game absence and his reliable partnership with Nemanja Vidic swamped Torres and forced Didier Drogba to hunt wide and deep for scraps of possession.
Organised in defence and quick to break, United created an excellent counter-attacking goal when Michael Carrick swept a pass into the path of Giggs.
The Welsh winger killed the ball with his first touch, hit the byline and pulled it back into the path of Rooney who steered it past Cech via a post.
Torres's only notable contribution of the first half was to miss Drogba's cross-shot, wrong-footing Edwin van der Sar and allowing the ball to hit a post. An off-balance Lampard got a piec
