Ramos has established himself as an indispensable part of Real’s backline over recent years but his stock has risen further following a number of key goals over recent weeks.
The defender has netted three headers in his last two outings and looks to be the main threat for Los Blancos when they are attempting to salvage a result late in matches.
Aduriz, who knows Ramos well from their time together with Spain, expects the defender to be a threat when they go head-to-head at San Mames on Saturday.
"I don't know who will have to mark Ramos - but whoever does has a big challenge," Aduriz said.
"We will try to mark him as best we can.
"It really stands out that a player like him does the same thing over and over again. His capacity to attack the ball is overwhelming.
"Real Madrid is one of the best teams out there - we know in order to get a positive result we need to play a perfect game and have a good day. We can make life very difficult for them."