Europe trail the US 10-6 heading into the singles matches at Medinah on Sunday, the final day of the competition.
"We have a tough task ahead, but I believe it's not over," captain Olazabal is quoted as saying by the BBC. "That's what I learned from Seve [Ballesteros], and that's what I'm going to pass to the players.
"Things have not gone our way, especially on the greens, but I believe that momentum will come our way.
"We are trailing by four points and we have to put the players that are playing well up there. If we want to win this match we have to take the big guys down."
Europe need to score eight points to retain the Ryder Cup, while the US need four and-a-half points to win it.