and the Ecuadorian drilled in a centre that van Persie blasted beyond Cech for his sixth goal in his last three games at Stamford Bridge.
Chelsea mounted an inevitable response with Luiz's swerving free-kick booted away by David De Gea and Eden Hazard pulling a shot wide following an outstanding jinking run. With Rio Ferdinand making some important clearances, despite being booed by the home crowd, United seemed in control until Roberto Di Matteo's team upped the pressure as the break approached.
Evans deflected a John Obi Mikel cross against the outside of his own post from a quick throw-in and the tireless Rooney diverted Gary Cahill's header off target from the resulting corner. It became one-way traffic and only a brilliant diving stop by De Gea kept out Torres' header from a Mata cross.
It became merely a question of whether the Reds could hold on until the half-time whistle and Rooney's rash trip on Hazard, earning a rare yellow card for the England international, presented Mata with an ideal opportunity in the centre of the goal, just outside the box. The Spaniard, thwarted by a De Gea wonder-save in the closing stages of last term's 3-3 draw, this time got the better of his compatriot with a perfectly-placed free-kick.
A poor kick-out by De Gea allowed Mata to scamper onto a Torres pass but the keeper atoned with a fine block as United went into the interval