Wayne Rooney says Manchester United must improve following Sunday's 4-1 defeat to local rivals Manchester City.
Last season's Premier League champions were blown away by Manuel Pellegrini's side at the Etihad Stadium, but Rooney made the scoreline slightly more respectable with a fine consolation free-kick in the closing stages of the match.
"It's not nice to lose to City by four goals to one. To lose by any score is bad, so we're all really disappointed," Rooney, who was the visitors' best player, told Manchester United's official website.
"The way we conceded the goals, one just before half-time and two straight after, is not good enough. We know we have to improve on that, to stop giving these sloppy goals away and capitalise on some of our good play, which I thought there was bits of... it just came too late in the game."
United played the best football after going 4-0 down, and Rooney believes this is because the players were desperate to salvage some pride.
"We knew at 4-0 that we obviously weren't getting back into the game but we had to keep fighting and pressing, trying to make a game of it to show the fans, and ourselves, the pride we have as footballers as it's never nice to lose," the England international continued.
"I thought during the last twenty minutes we played some good stuff. Had we done that earlier there might have been a different outcome, but it was too little too late."
David Moyes' men now turn their attention to Wednesday's Capital One Cup clash against fierce rivals Liverpool, a match which will provide United with a great opportunity to put Sunday's derby humiliation behind them.
Rooney added: "Thankfully we've got the game against Liverpool coming up Wednesday and it's something we are looking forward to now in the hope that we can get the victory to put this defeat to the back of our minds."