Former Portugal international Rui Costa has urged Seleccao supporters to get behind Cristiano Ronaldo rather than criticise him for his performances.The Real Madrid ace has frequently come under fire for his form at international level, with many critics suggesting that he does not give his all for his country.But as Portugal prepare to take on Bosnia and Herzegovina in the decisive Euro 2012 play-off at the Estadio da Luz, Rui Costa has called on the Seleccao fans to back the 26-year-old."No-one will want to make the difference in Tuesday's game more than Cristiano Ronaldo," Rui Costa told reporters. "To be criticised by other teams is a sign of his importance."What cannot happen is him being criticised by our fans and our country. He is one of the best players in the world, he is the captain of the team and we have to be proud to have him with us."We cannot think he will have to decide the match alone, but that he will do everything to make Portugal qualify for the Euro 2012 finals."The Seleccao host Bosnia and Herzegovina at 22.00CET hoping to seal qualification for Poland-Ukraine after the goalless draw in Zenica on Friday.