United Manager Jose Mourinho won titles during his two stints with Chelsea, which both ended in firings, and he arrived at Stamford Bridge here on Monday for the quarter-final contest with what seemed like a sound plan, reports Efe.
Unfortunately for him, his charges were overzealous in their efforts to neutralize Blues striker Eden Hazard.
The visitors found themselves down to 10 men with 10 minutes left in the first half after Ander Herrera drew a second yellow card for bringing down the Belgian international right after the referee warned United captain Chris Smalling that the next Red Devil to foul Hazard would be penalised.
Playing without the suspended Zlatan Ibrahimovic, United emphasized defence against the Premier League leaders.
The visitors managed one chance before losing Herrera, a shot from Henrikh Mkhitaryan in the 12th minute that went wide of the right post.
United goalkeeper David De Gea, meanwhile, had to be sharp to parry threats from Hazard and Gary Cahill.
With Herrera's sending off, the Blues took firm control of the match with a multipronged attack full of movement from side to side.
Chelsea's dominance bore fruit in the 51st minute in the form of a rare goal by midfielder N'Golo Kante, who is better known for his outstanding defensive play.
The Blues retained their advantage on possession, but failed to get a second goal, leaving the door open for United to get back into the contest.
The equaliser seemed within reach in the 59th minute, when speedy Marcus Rushford blazed down the field on the counter only to lose the one-on-one battle with Chelsea keeper Thibaut Courtois.
Chelsea will now take on Tottenham Hotspur in first semifinal and the other tie will feature Arsenal and Manchester City.