By John Geddie MARSEILLE, France (Reuters) - Poland have an impressive defensive record at Euro 2016 but standing in their way to a semi-final spot is arguably one of sport's greatest-ever athletes, Cristiano Ronaldo. The monstrous Polish center back pairing of Michal Pazdan and Kamil Glik face their toughest challenge yet when they come up against Portugal in the last-eight clash in Marseille on Thursday, though their previous matches have not provided much by way of preparation for facing the Real Madrid star. Describing 29-year-old Ronaldo as the "perfect athlete", U.S. lifestyle magazine Men's Health says he hits speeds of more than 32 kph, jumps nearly a meter in the air off one leg, runs an average of 16 km per match and hits more winners in the last 20 minutes than anyone else. More...