United, who will be missing injured striker Wayne Rooney, have won just one of 18 away games against Spanish opponents, with eight draws and nine defeats, and failed to score on their last three trips to the Iberian nation.
"It's always the hardest place for us to go if you give me that statistic," Ferguson said at a news conference at Valencia's Mestalla stadium on Tuesday.
"The standard of Spanish football has always been very, very good. It's a difficult place to win, there's no doubt about that.
"That's the great thing about the European Cup. You always get to play against fantastic teams in Spain, Italy and Germany. That's what makes it such a great tournament."
"Valencia's home record over the years has been very good and we respect that," Ferguson said.
"They're very strong defensively and they don't surrender anything easily.
"Hopefully we can impose ourselves tomorrow the way we know we can."
"He's much fitter now but probably needs another game or so," Ferguson said, adding that he had no complaints about the recent performances of Jonny Evans and Nemanja Vidic.
"It's a decision I'll take tomorrow about whether he (Ferdinand) starts or not but we're looking forward to having him back."
