England international hails shock victory after his side humiliate their local rivals to extend their lead over the Old Trafford side at the top of the league to five points
Braces from Mario Balotelli and Edin Dzeko, as well as further goals from Sergio Aguero and David Silva, sealed the win for City.
The victory sees them go five points clear of United, who had Jonny Evans sent off early in the second half, with Darren Fletcher getting a consolation goal for the hosts.
Richards told Sky Sports: “It’s what dreams are made of, we all know how good United are and how good they are at home.
“But, they know we’re an attacking force with David Silva, Dzeko, Aguero and Balotelli. [They] were unbelievable, so it was a good performance all round.”
He added: “To be honest, I’m still gobsmacked, to come here and get a point would have been a great result, but to come here and win 6-1 is just unbelievable.
“They had 10 men [in the second half] but in the first half I thought that we played well and took our chance when it came and it’s a good foundation to start and hopefully we can kick on from now.”
Richards is now targeting further improvement after the win over United took City's points tally for the season to 25 after just nine games.
He continued: “To come to Old Trafford and win and especially the way we won...and like I said, we’ll take it from here.”
When asked what kind of message this sends out to the rest of the league, Richards said: “People call us the noisy neighbours and here we are, we’ve got a good set of lads now and we want to show people what we can do and I think we did that today.”
Richards was then asked about the t-shirt Balotelli revealed after his first goal, which read ‘Why Always Me?’, to which the defender responded through fits of laughter, saying: “I didn’t see what it said, what can I say? He’s an incredible character and he played well today.”
The right-back also said it was a good feeling to stand in front of the City fans after a famous victory over their rivals.
He said: “It was unbelievable, I did a programme the other day that I’d played in 11 derbies and had lost seven, so to win one today was a nice feeling.”