Borussia Dortmund coach Jurgen Klopp believes that the key to defeating Real Madrid is to stop midfielder Xabi Alonso from playing his game.

Klopp masterminded a 2-1 home win for Dortmund against the Spanish champions and then held Jose Mourinho's side to a 2-2 draw in Madrid in the group stage of the Champions League this season.

"We knew where they would send their passes, how they look for Cristiano [Ronaldo]," he told El Pais. "Our plan was to take Xabi [Alonso] out of the game.

"Because if Alonso can play as he wants it is impossible to defend against Madrid. And [Mario] Gotze covered him.

"We knew that if our full-backs, [Lukasz] Piszczek and [Marcel] Schmelzer, moved around a lot, the advantage would be on our side against Cristiano. If you block Xabi, you make it so Pepe always has the ball. That is a big difference."

Madrid will host Manchester United in the first leg of their Champions League last-16 tie at the Santiago Bernabeu on Wednesday.