Last season's Champions League winners must overcome a deficit to reach the Europa League quarter-finals after falling to a 1-0 loss in Romania last night after Ryan Bertrand conceded a penalty, scored by Raul Rusescu.
The Blues have no time to wallow in self-pity, though, following the poor performance as their FA Cup defence continues at Old Trafford in their second game in four days.
"It's the best way to forget about this defeat," Cech told Chelsea TV.
"The games are coming thick and fast. We won't have much time to prepare, but we'll get a little bit of rest and hopefully we'll have a good performance on Sunday.
"They are the favourites for the game, but it's the FA Cup and in the FA Cup not every time do the favourites win.
"We're still the holders, so we'll try to keep our trophy as long as we can."