Patrice Evra tackle on Ramires late in the game at Stamford Bridge causes controversy as Spanish referee Alberto Undiano Mallenco denies hosts - then later books Torres for diving
As had been the case in their Premier League meeting last month, Wayne Rooney scored the first goal for United - and just as had been the case last month, a referee's decision over a penalty claim has left one side nursing a grievance.
Last time, it was Martin Atkinson who gave a penalty for Chelsea after Chris Smalling's challenge on Yuriy Zhirkov, presenting Frank Lampard with the opportunity to complete a 2-1 victory for the reigning champions.
This time, it was Spanish referee Alberto Undiano Mallenco who was the man in the middle and at the centre of controversy.
He had enjoyed a relatively trouble-free evening until injury time, when Chelsea midfielder Ramires latched onto a long ball and was through on goal - except for the attentions of United defender Patrice Evra.
The Frenchman slid in on his opponent, and the pair came crashing down to the turf.
Replays suggested Evra had not played the ball and had prevented Ramires from advancing with a scissor tackle that took the Brazilian's legs away from him.
But referee Mallenco waved play on, believing the United man had won the ball fair and square.
The controversy was in no way over however as Fernando Torres, who disappointed once again for the hosts, tangled with Antonio Valencia in the box and fell the floor. Mallenco waved away the Spaniard's protests for a penalty and booked him for simulation.
What do you think? Vote in our poll below - and don't forget to have your say by leaving a comment.