Borussia Dortmund CEO Hans-Joachim Watzke has welcomed the idea of any Real Madrid player joining his club ahead of Wednesday's Champions League tie.
The two sides will meet for the third time in Europe this season when they take to the field for the semi-final first leg, with the Bundesliga outfit already having beaten los Blancos 2-1 at home and securing a 2-2 draw in Madrid in the group stage.
Speaking in an interview with German sports programme Sportstudio, Watzke admitted that any of Jose Mourinho's players would be valuable at BVB, although he warned that Cristiano Ronaldo would need to improve defensively.
"Every Real Madrid player would fit in at Borussia Dortmund - they are all world class," the 53-year-old stressed.
"Ronaldo too, of course. However, he would have to work a little bit more in the defence."
Dortmund are a distant second to new Bundesliga champions Bayern Munich this campaign but their European ambitions are very much intact - something Watzke attributes to the strength of the squad underpinned by their transfer policy.
"If you invest in the quality, you automatically gain depth," he continued.
"Our only limit is that we won't agree to a monetary loan to sign players, but other than that, there are no restrictions."