The two clubs from Manchester are neck-and-neck in the race for the league crown this season and April's game at the Etihad could well decide what colour the city will be painted at the end of the campaign - red or blue.
United and City are level on points for now (although Sir Alex Ferguson's side has a game in hand) and Valencia knows the local derby will be of crucial importance.
Meanwhile, United's boss has picked out Valencia as the key in United's bid to defend the Championship. Ferguson pointed out the impact that Tevez, who was restored to City's first team after a six-month argument with manager Roberto Mancini - Tevez came on as a second half substitute against Chelsea and set up Samir Nasri's late winner.
