The build-up to this game had been overshadowed by a Football Association charge hanging over Rooney’s head following his antics this past weekend, but the England striker was on top form as United drew first blood against their fierce rivals.
Didier Drogba brought a smart save out of Edwin van der Sar as the Blues threatened first, but it was United that went ahead on 24 minutes when Michael Carrick found Ryan Giggs with a superb diagonal pass, and the veteran midfielder produced a sensational touch to create space for him to pull the ball back for Rooney to stylishly slot home.
Chelsea almost snatched an equaliser on the stroke of half-time, but van der Sar kept out a Drogba effort and Frank Lampard’s follow-up was cleared off the line by Patrice Evra.
United suffered a setback in the early stages of the second half when full-back Rafael da Silva was forced off following a collision with Drogba, and they fought a brave rearguard action as Chelsea desperately sought a late leveller.
Fernando Torres went agonisingly close to netting his first goal for the Blues when his superb header was pushed away by van der Sar, and the London club were then angered by a controversial finish.
Chelsea had a penalty appeal waved away when Evra appeared to bring down Ramires with a clumsy challenge in the area, and Torres was then booked for diving in the United box as the visitors held on to take a one-goal advantage back to Old Trafford for the second leg.