By Mike Collett

DONETSK (Reuters) - Seven Real Madrid players are likely to be on opposing sides when Portugal face Spain in their Euro 2012 semi-final on Wednesday with one particular battle capturing most attention.

Spain defender Alvaro Arbeloa is set to be the man assigned to shackle club mate Cristiano Ronaldo, who has already scored three goals and hit the post four times at these finals and is emerging as the main contender for player of the tournament.

As well as Arbeloa and Ronaldo, Real Madrid team mates will be battling for supremacy all over the pitch with goalkeeper Iker Casillas, Sergio Ramos and Xabi Alonso wearing Spain's colors while Pepe and Fabio Coentrao also line up for Portugal.

Asked if he had had a chance to meet up with Ronaldo before the game, Arbeloa, said he had not talked to him yet.

"No I haven't spoken to him, I will probably speak to him tomorrow when I see him," said the Spain defender.

"We all know how well he is playing at these Euros. It is very hard to play against him, he is very confident, he is playing very well, but we will try to stop him."

Arbeloa added that he was more than prepared for the challenge against his club mate.

"Of course, you have to be mentally and physically prepared to play against someone like him. He is one of the best players in the world, so you have to be on top of your game.

"I know how hard it will be to stop him for 90 minutes, but it will be a beautiful challenge for me. I want to measure myself against the best in the world and it's a great challenge to face him."

FAMILIAR FOES

Club mates playing against each other is nothing new in international football, but it is rare for one club to provide so many on opposing sides in one match at a major finals.

In all, 10 Real Madrid players have been involved in the tournament but there is no doubt who is dominating the thoughts of the Spanish team.

Ronaldo, of course, knows most of Spain's players at least as opponents with the Barcelona contingent of Andres Iniesta, Cesc Fabregas, Sergio Busquets and Xavi all familiar foes.

Iniesta, though, was also highly complimentary about Pepe, the Real center back who will be at the heart of Portugal's defense on Wednesday.

"Of course I know him well, as a tough opponent. He is one of the best center-backs in the world. He can attack, he is fast and he is dangerous. We are going to have to be at our best to beat them."

Iniesta said he was not pre-occupied by the intense club rivalry that underpins one of the world's great international derbies.

"All I am thinking about is Spain getting through to the final and lifting the trophy again. It is my only thought, nothing else is important.

"Every individual has to work for the team, that's all I am thinking about."

(Reporting by Mike Collett; Editing by Ken Ferris)