Substitute Sam Saunders struck a second-half winner to give the Bees a 1-0 victory over Crawley, their second triumph over the Red Devils in the space of four days, and a place in the last eight.
"I think we deserved it," O'Connor told Bees Player. "We started really well in the first 20 minutes and then it probably evened out a little bit.
"They had a few chances, so did we. Once we got it down and played, rather than going long, we cut them open and had the clearer chances.
"We started like we did last Saturday but they grew in to the game. It was an even game, but, chances wise, we deserved it.
"You always feel that a goal might not come when time is running out but we kept going and Sam came up with a good finish."