Real Madrid captain Sergio Ramos says French teen striker Kylian Mbappe will become a welcome addition for the reigning Champions League and La Liga champions should he decide to leave Monaco.

The 18 year-old forward is wanted by Real Madrid manager Zinedine Zidane, with the Spanish giants poised to make him one of the most expensive players of all time in a move that could cost around $211 million (€180 million).

Ramos was adamant Mbappe has the qualities to become of the best in the world.

"It's not a decision for me but Mbappe is a great prospect. There are not young players around like him. We have an important year ahead of us and already have excellent players," Ramos said ahead of Saturday's meeting with arch-rivals Barcelona in Miami.

"But it's money which moves football and people can pay what they want. If he wants to come to Real Madrid, the doors will be open."

While Zidane smiled through his press conference here, Barcelona have been fighting to keep superstar Neymar from accepting Paris St Germain's riches. The French legend declined to twist the knife regarding Neymar.

"We will see what happens," Zidane said. "He's a good player. They are our most important rivals but we lost our last match against Manchester City and we want to put in a strong performance.

"We are happy, want to perform, we want to be physically better. That's our goal, but we are so happy to be here."

Madrid will boast a strong squad although Real enters the match without Cristiano Ronaldo, who has missed the US tour and will not appear Saturday.

"Yes I am happy with what we have right now," said Zidane. "But we have a good squad even though we are missing Cristiano here. He is on vacation, and he can enjoy that and be ready for the season."

Ronaldo kept the International Champions Cup organisers waiting until the very last minute before deciding he would not be playing.

The Portuguese star has been in Asia completing commercial obligations and is expected in court on Monday in Madrid to testify in a tax-evasion case, meaning his presence in South Florida was always highly doubtful.

"Unfortunately, Ronaldo's personal commitments precluded him from being here," Charlie Stillitano, chairman of organisers Relevent Sports, told the Miami Herald.

"He really wanted to be here. This is not a diva situation. He was hoping that he could make it. He waited until today to let us know, but it just didn't work out. We still have the two best teams and the top stars minus one."