United drew their opening game 0-0 at home to Rangers and will be desperate to avoid defeat against Unai Emery's men - who finished third in La Liga last season.
For fans making the trip there are several options available.
If you fancy making the trip by ferry, why not check out Cheap.co.uk's ferry booking service.
If it's a flight you're after, you'll need somewhere to park your car at the airport. Try this site for size.
When you arrive in Valencia you could opt for public transport, or alternatively rent a car. Cheap.co.uk Car Hire is a good place to look.
However you get to the game, make sure you have travel insurance in place. After all, you never know what might happen! Take a look here to find the cheapest travel insurance on the internet!