Real Madrid are bracing to face a trickier, more experienced Ajax squad on Tuesday than the one they beat 4-0 last year at the same stage in the UEFA Champions League, the Spanish club said.
"Ajax are better now than a year ago. They are bringing practically the same team, have spent a year working together, and have more experience," Real's assistant coach Aitor Karanka said.
"We are expecting quite a difficult match, not as winnable as last year," he said, standing in for coach Jose Mourinho, who is serving a UEFA ban after an ill-tempered Champions League clash with Barcelona last season.
A victory against Ajax in Madrid on Tuesday night will all but guarantee a place in the knockout stages for Real from qualifying Group D, which also includes Lyon of France and Croatia's Dinamo Zagreb.
Real's star striker Cristiano Ronaldo scored twice in last November's 4-0 victory in Amsterdam, which knocked the Dutch side out in the group stage, with one goal each from French striker Karim Benzema and defender Alvaro Arbeloa.
"I was impressed by what we saw this morning," Arbeloa said, after watching Ajax train today. "This is an Ajax that has spent a year working together, an Ajax with a lot of speed up front and wingers who can throw you off balance."
Real are the most successful club in Champions League history with nine titles, but the pressure is mounting on them to seize the trophy again after ten seasons without winning the event.