Manchester United manager David Moyes said he upbraided his players after their crushing 4-1 derby defeat at Manchester City and called for an immediate improvement in their performances.
The Scot had a torrid experience in his first Manchester derby, as a Sergio Aguero brace and goals from Yaya Toure and Samir Nasri gave City a victory reminiscent of their seismic 6-1 win at Old Trafford in 2011.
It was United's second defeat of the season, leaving them five points behind Premier League leaders Arsenal in eighth place, and Moyes admitted that he had vented his spleen at the final whistle.
Asked if he expected a reaction in the changing room, on the training ground or in the next match, Moyes replied: "All of them, and I've made them aware of that as well.
"But I think if there was ever a group of players who I would expect that from, it would be from Manchester United players.
"The way they're been brought up, the previous manager [Alex Ferguson]. They react, and that's what we'll do here. Every manager has bad days and bad results, and I'm no different."
Moyes enjoyed a fine record at the Etihad Stadium with former club Everton, winning on four of his last six visits, and he appeared slightly baffled by the poor quality of his new side's display.
"I've been here with Everton many times and I don't think I've ever suffered a defeat like that when I've been here with Everton," he said.
"I just told the players the way I would have told any other players if I don't think they're doing it. They're good players here, good pros, and they know when they're bang at it and when they're not."
The defeat followed a 1-0 loss at Liverpool and a 0-0 draw with Chelsea, and having complained about United's daunting start ahead of the season, Moyes hopes things will improve as the campaign progresses.
"We want to win more of those games, we have to do that," he said. "But maybe if those games are late in the season and not right at the early part of it, then I might have a better understanding of all the players, the situation at the club.
"I think any manager who'd have been given that run of fixtures when they took over at this club would have found it difficult."
City manager Manuel Pellegrini will have far happier memories of his first Manchester derby, having seen his side climb to third place in the table with a brilliantly assured performance.
Asked if City had struck a big psychological blow against their cross-town rivals, he replied: "Very big. Always, winning against Manchester United and the way we win, is always an important impact."
He said the nature of his side's performance, in which man-of-the-match Nasri played a part in all four goals, would also help him to introduce a more expansive style of play than that of his predecessor, Roberto Mancini.
"I would be very happy if we win all the games 4-1. We wouldn't need to improve anything more," he said. "I think we are just starting another style, another way to play, and I hope we will improve every day."
Although Robin van Persie missed out for United with a groin strain, Moyes said the injury was "not that bad", suggesting the Dutchman could feature against Liverpool in the League Cup tomorrow.
The Scot also sought solace in the performance of Wayne Rooney, who scored with a fine late free kick to become the outright leading scorer in the history of the Manchester derby with 11 goals.
"Obviously we miss Robin van Persie, it's a huge miss to anybody," Moyes said. "But I thought Wayne Rooney could have arguably been the best player on the pitch today. He certainly didn't deserve to play on the losing team. He was outstanding today and what I remember back to probably as good a Wayne Rooney as I've seen, on that showing today."