Manchester United's Jose Mourinho will manage Real Madrid 'sooner or later' - Ramon Calderon

Former Real Madrid president Ramon Calderon has told ESPN FC that Jose Mourinho will return to the club as manager "sooner or later."

Julen Lopetegui was brought in as a replacement for Zinedine Zidane in the summer after the Frenchman had stepped down on the back of winning three Champions League titles in a row. However, following a run of one win in six matches, there are reports the former Spain boss could face the sack heading into Sunday's Clasico.

One of the names touted as a potential replacement is Mourinho -- and Calderon said it is only a matter of time before the Manchester United boss returns to the Bernabeu, given his relationship with Florentino Perez.

"If this president is with the team for a few years, and I think he will be, Mourinho will be here," he said. "No doubt. It's the only coach the president has respected.

"For better or worse. I think he will be here -- if he leaves Manchester, of course. But sooner or later, I think he will be here."

Calderon also labelled Real Madrid's decision to sell Cristiano Ronaldo to Juventus for €100 million as a "historic mistake."

Calderon was the man behind the deal which brought Ronaldo to Spain from United in 2009 -- though it was at the start of Perez's second term that the move eventually happened. The Portugal international finally left the Santiago Bernabeu earlier this year after scoring 450 goals in nine years.

Aside from their UEFA Super Cup defeat to rivals Atletico, Madrid started the season in good form but they have struggled in the last month. In the midst of their poor run, they went 481 minutes without a goal -- leading to suggestions they miss Ronaldo.

"I think it's been a big mistake, a historic mistake in many senses," Calderon said. "And with no replacement! There's no way to find someone to substitute a player like Ronaldo, so [it is] a big mistake.

"If you see that the €100m we've received has been spent on two players: one is in Brazil, Rodrygo, and the other [Vinicius Jr.] is playing in Castilla [Madrid's reserve team]. [It's] something very weird. I have all the respect for Mariano [Diaz], but now he has many things to show until he can be at the level of Cristiano.

"It's going to be very difficult [to replace Ronaldo]. Not only because big clubs won't let [players] go, but also because of the price. It's very difficult to see what would be the limit for players after the €220m spent on Neymar. Now every player is worth more than €200m.

"So [Eden] Hazard, [Harry] Kane, all of them, Neymar of course, will be difficult to sign. The economy of the clubs is not unlimited. So you can pay for one player, but now we are involved in a project of €600m building the stadium."

Perez eventually succeeded Calderon as Madrid president, via Vicente Boluda, in 2009. The two have never seen eye-to-eye and Calderon said that Perez, a civil engineer, is too "whimsical" in his decision making.

Calderon also said he believes there should be a sporting director between the coach and the president, and that Lopetegui should be given more time regardless of the result of this weekend's Clasico between Barcelona and Madrid at Camp Nou.

"I think one coach must have at least one year on the bench," he said. "But this club is very demanding. Only one coach in the last 48 years has been more than three years on the bench. There is no patience. And if you lose matches and you don't play well, fans are going to boo the team.

"And the president is always [under] pressure to decide. I think in Lopetegui's case it's too much [to sack him now]. I wouldn't, I would wait. Reading and listening [to the press], they're looking for a new coach. That's bad for us and for the current coach, who is under big pressure.

"I don't think the way to solve it is to sign another coach, because the one who comes in will have the same team. He cannot change anything. I would say it wouldn't be wise to sack the coach now, regardless of the result on Sunday."