Premier League champions United hope a resounding victory on Saturday over lowly-placed WolverhamptonWanderers at Old Trafford will provide the perfect tonic for their mid-week hangover.
The bitter disappointment of getting knocked out at the Champions League group stage by Basel has been compounded by an injury to defensive rock and club captain Nemanja Vidic.
The Monday night clash between England's wealthiest clubs will also be seen as a make-or-break game for Chelsea as it offers Roman Abramovich's team a chance to rescue their Premier League season.
Manager Andre Villas-Boas held up the clash at Stamford Bridge as a potentially defining moment of the season that could re-ignite Chelsea's domestic title challenge and playmaker Juan Mata agreed.
"It is not impossible," said the Spanish World Cup winner. "There are so many weeks until the Premier League finishes. We will keep going every week to win and to be closest to the leader.
"They are the leaders, they win in every game and we hope that here at Stamford Bridge they will have a difficult game," added Mata.
"We lost against Liverpool, against Arsenal, against Manchester United, but we hope that against Manchester City we'll change this."
"He has been in a fantastic moment and is sure to threaten for the starting 11 on Monday," said Villas-Boas, who complained after the Valencia game that City were given a far easier ride by the media over their European difficulties.
