The former Blancos midfielder, who is now back at Borussia Dortmund, feels the Clasico duo will be driven on by the pain of their Champions League semi-final exits last term
Many pundits tipped the Clasico duo to reach May's final at Wembley but the biggest game in club football was instead an all-German affair between Bayern Munich and Dortmund.
However, Sahin, who has returned to Germany from Madrid via Liverpool, believes the Spanish will bounce back this term.
"The Spaniards were really hurt by last season," the midfielder told Kicker. "That will trigger a reaction, I'm sure.
"They have dominated European football in the last six to eight years, and Real Madrid and Barcelona will be very strong in the coming year.
"However, the Bundesliga is on the right track and will continue to play a role."
On a personal level, Sahin is now hoping to get his career back on track and feature with greater regularity in the Champions League this season, having been forced to play a bit-part role in Dortmund's run to the final following his January arrival from Liverpool.
"I now want to play in the really big games in the new season," he confessed. "These games are the dream of every professional.
"I know I can play my part in ensuring that we reach a higher level. But, at the moment, I am just happy that after two years I can finally start a campaign having done a full pre-season."
Sahin left Signal Iduna Park for the Santiago Bernabeu in 2011 but failed to settle in the Spanish capital, making just four La Liga appearances for los Blancos.