Madrid caused a huge stir in 2001 when they signed Zidane from Juventus for a world-record fee of $90million and Florentino Perez is creating similar waves now after returning to the club presidency a fortnight ago.

Perez has already spent $110million on Brazilian ace Kaka, while both that fee and the price paid for Zidane are set to be dwarfed after Madrid's offer of $160million for Cristiano Ronaldo was accepted by Manchester United.

Madrid's incredible spending spree during a global financial crisis has led to plenty of debate and criticism, but Butragueno believes the investments will be worthwhile if the return is the same as Zidane provided during his five seasons at the Bernabeu.

"When Zidane was signed in 2001, everybody also thought that it was a lot of money. However, now nobody doubts that he was a profitable signing for Real Madrid," said Butragueno, a legendary former striker at Madrid and now the club's newly-installed director of institutional relations.

"It was worth it all to pay this money, for everything that he did in this stadium and what it meant for the club.

"There are signings of 15 or 20 million euros who do not perform and signings that cost what Cristiano and Kaka do, who do perform.

"I hope that all the players that sign for Real Madrid give the kind of performances that Zidane gave. That would be great for the club."

He added: "The fans demand to have the best players in the world. They are used to seeing its team win and playing well, so signing the best players is very smart."

Although Kaka is already in the bag, Madrid are still to confirm the signing of Ronaldo.

The Spanish giants expect to agree personal terms with the Portugal international in the coming days, and Butragueno is expecting big things from the FIFA World Player of the Year.

"Cristiano Ronaldo is going to give us great energy, speed, and goals. He is a complete player and from a footballing point of view he must be a key player for us," he said.

Kaka and Ronaldo are not set to be the only star signings joining the club this summer, with the likes of David Villa, Franck Ribery and Xabi Alonso also linked to Madrid.

That would suggest a bleak future for any Madrid youngsters hoping to break into the senior squad, but Butragueno prefers to look at the positives.

"I honestly think that it is very good that players like these come to the club. They will also set a good example for academy players if they happen to be great professionals," Butragueno added to Telemadrid.

"It's worse to sign a player who is not so good. Players such as Kaka and Cristiano will contribute many things to the youth team. These are the players that Real Madrid must always have."