Accrington Stanley boss John Coleman said Will Grigg's goal on the stroke of half time was the key moment in Sunderland's emphatic win.
The Black Cats had been the better side by a distance in the opening half after an outstanding strike from Aiden McGeady put them ahead just three minutes in.
They had pushed hard for the second goal and it finally came when a Jon McLaughlin clearance found its way to Grigg, who finished excellently.
"They're a good side," Coleman said.
"But you know, they're coming here on the back of a harsh defeat at Wembley, which would have been confidence and energy sapping.
"Then they get a shot of adrenaline. You can't give a player of Aiden McGeady's ability time and space to get the ball, walk inside unopposed and get a ball in from 20 yards. It's a great finish.
"They were very, very good for half an hour for that," he added.
We had our hands full to stay in the game which we did, we had a good chance that Billy [Kee] put over the bar.
"They were comfortably the better side in the first half but if we go in at 1-0 then it's a completely different game. To concede the way we did, we got a let off a minute earlier with a ball over the top, if you defend like that you'll get punished at every level but certainly when you've got good players, £3 million strikers, you expect to get punished."
Coleman was pleased with his side's response at the beginning of the second half after changing shape.
Jack Baldwin made an outstanding block, Jon McLaughlin an excellent save as Sunderland preserved their lead, Kazaiah Sterling eventually killing the game with a good late finish.
"What I must say is that first 25 minutes of the second half I thought we were outstanding," Coleman said.
"We pinned them back, made three glorious opportunities.
"We're throwing the kitchen sink at them, we were prone to getting picked off and they did that, once they get the third goal it is game over.
"My own personal opinion, they were better than us on the night but for 25 minutes we were better.
"The game has hinged on the second goal for me and when we see it again we'll be very disappointed."