Manchester United striker Wayne Rooney admits the Premier League champions were not 'good enough' during Sunday's humbling at the hands off rivals Manchester City.

Manuel Pellegrini's side put four goals past the Red Devils at the Etihad Stadium, with Sergio Aguero finding the net twice and Yaya Toure and Samir Nasri also finding the net for the home side.

Rooney was able to pull a goal back late on - a superb free-kick - but it was far from a consolation for Manchester United with the game already beyond them, and the England international was in reflective mood after the contest.

"Disappointing game yesterday, our performance just wasn't good enough," Rooney told his official Facebook page.

Manchester United must now recover quickly for another derby encounter on Wednesday, this time with Liverpool in the Capital One Cup, and Rooney believes a meeting with the Reds is precisely what is needed after defeat to City.

He added: "It's up to us as players to put it right now and there can be no better game to motivate us than facing Liverpool in the cup on Wednesday."

Manchester United lost 1-0 to Liverpool only three weeks ago, and will be desperate to make amends against their fierce rivals when they host Brendan Rodgers' side at Old Trafford.

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