Real Madrid forward Cristiano Ronaldo has a 1 billion pound release clause in his contract, according to his agent Jorge Mendes, who told the BBC that the Portuguese star would sell for 300 million pounds if the club decided to let him leave tomorrow. Jorge Mendes described the 29-year-old forward as the "best player ever" and the "best sportsman ever." Mendes added: "You can't compare him with anybody else."Ronaldo was voted the world's best player for a third time last month, beating Barcelona rival Lionel Messi to the prestigious award.Asked how much he was worth, Mendes said: "Cristano Ronaldo? One billion pounds. His buyout clause is 1 billion, so it is 1 billion. If, for any reason, the club decide to sell him tomorrow for 300 million pounds, someone will pay."Mendes oversaw Ronaldo's move from Sporting Lisbon to Manchester United for 12.24 million pounds in 2003 However, Mendes insisted his countryman, who cost Real Madrid a world record fee of 80 million pounds in 2009, would stay at the Bernabeu, despite his "love" for the supporters of his former club Manchester United. "He will not leave Real Madrid," Mendes told BBC sports editor Dan Roan. Mendes also said that Cristiano Ronaldo showed his professionalism by representing his country at the 2014 World Cup despite an injury. Ronaldo was suffering from tendinosis in his left knee when he played in the Champions League final before taking part in the World Cup in Brazil.Although Cristiano Ronaldo failed to perform at his best at the World Cup, his agent said that during the launch of his biography, "The Mendes Key," Ronaldo had shown his commitment by showing up to the tournament. Mendes added that Ronaldo always wants to play. The 29-year-old, who will turn 30 on Feb. 5, has scored 36 goals in all competitions this season. Mendes, who is reported to have brokered more than 1 billion pounds worth of transfers, has been described as the most powerful figure in the game. "People have the wrong idea about agents," said Mendes. "Being an agent means many different things. I'm someone normal, I'm working hard every single day. I have ambitions, determination and being honest, doing the right things... this is most important."He described football as the "most important sport in the world" and defended the wages players now command, saying they "deserve the maximum possible." Mendes compared working with his players on contracts as "like a family." "It is like when you talk with your son, with your family... always to try to find the best way to support them," he said. Mendes also described the ban on third-party ownership of players as "illegal" and "catastrophic" for clubs."Fifa and Uefa are not the police," he said. "I think that it's very important to establish rules, the right rules, but not to stop it."Mendes, a former DJ and nightclub owner, also represents Jose Mourinho, Luiz Felipe Scolari, Radamel Falcao, Angel Di Maria, James Rodriguez, David De Gea, Victor Valdes and Diego Costa.He negotiated Angel di Maria's 59.7 million pound move to Manchester United and Diego Costa's 32 million pound purchase by Chelsea last summer.