He had cut an animated figure on the touchline in the first half, forcefully trying to galvanise his stuttering side.

But afterwards in the Press Room he was purposely subdued. The inquest into what went wrong will have started in earnest afterwards.

He said: "I can't put my finger on why we played like we did, but I'm sure I will in the next few days.

"It's very hard, straight after a game to to try and analyse it but some days in football it just doesn't happen.

"Some days you might have two or three players underperforming, but I can't think of a single player on our side who performed to the level we know he can.

"You can lose games in the Premier League if two or three are not really at it, so to have a whole team not at it, you're always going to be in danger of a big defeat.

"The first goal was hard to take. A bad goal. But I've seen them on the replays and they're all bad.

"The second and third coming in quick succession knocked the stuffing out of us and we never looked a threat after that.

"It became easy for City. It was a very bad day at the office. Very bad."

The Sunderland manager went on to consider where City had won the game and eventually couldn't escape the conclusion that his own side had come up short everywhere against a very capable team.

"You can look at systems and they were very strong in the middle," he started.

"But then they also defended well and had a goal threat. They had pace in the side and the big lad up front, the Brazilian, he's a good player who can handle the physical side of things.

"They just seemed sharper than us. They did everything better than us and when that happens, you are never going to win in football.

"They've got a good team, I have to say. They impressed me."

Things might have been different had one or two things gone Sunderland's way, and some bizarre officiating in the first-half did not help, but Keane would not go down that road.

"I don't want to sit here and try to make excuses about the new players bedding in or the first goal, or bad luck or the referee. I'm not going to insult anyone's intelligence about that in this game.

"The reality is we've lost a game of football 3-0. We are not happy about it. It is hard to take. But we have to accept it.

"I don't think it's a day for excuses. What we have to learn as a team is that we should look to grind something out when we're not playing well, but we're obviously not capable of doing that at the moment."

Now the manager will contemplate how to find a positive way back from this defeat in a season which he is determined will prove more successful than the preceding one.

He certainly has time on his hands to think things through, with Sunderland's next game, the visit to Wigan Athletic, almost a fortnight away.

"Every manager on the planet wants a positive result going into a break because it can be a long two weeks if you don't get one," he shrugged.

"We've been generally lucky in that respect, so I don't know how the next couple of weeks will be.

"Maybe it's a good thing though because I'll be glad to see the back of one or two faces. I mean that in a good way.

"People can go away on international duty and it can liven them up when they return. We'll see. We'll still have enough bodies to have some decent training sessions in the meantime.

"We have the reserves and we have training to help one or two with their fitness.

"Anton Ferdinand might get a practice game Thursday or Friday this week. He's still a long way from full fitness.

"Mind you if he watched the way we defended against City he'll be expecting to get his chance."