Both Branislav Ivanovic and Fernando Torres were shown red cards, the first for bringing down a player while being the last man and the latter for simulation.
It all helped United on their way to another win and their first Premier League win at Stamford Bridge for ten years.
And Michael Carrick was pleased with the victory.
"It's a huge three points," Carrick told MUTV.
"Not winning here for a long time against our biggest rivals, we wanted to put that right and we wanted to win for that.
"Plus the fact that if we had lost today we would've been well adrift. I know there's a long way to go, but it wouldn't have been a good position for us to be in. So for those two reasons it was a big result.
"Over the last three or four years we've had some really great performances here and not come away with what we deserved, so today it was sweet to get the three points."