The 53-year-old says that the Reyno de Navarra club will prove a tough test for the European champions, who must not take any of their cup opponents for granted.Barcelona\'s director of institutional relations Pere Gratacos has urged Pep Guardiola\'s side to respect Osasuna in the wake of the Copa del Rey last-16 draw.Should the European champions progress against Jose Luis Mendilibar\'s men, they could be in line for a mouth-watering clash against arch-rivals Real Madrid, but Gratacos has urged his side to take the competition one round at a time.\"We have to respect Osasuna, because they can easily win the two games,\" Gratacos told Marca.\"I think that we have to take things one step at a time, respect every opponent, and if we do our job well, we will progress.\"In principle, the favourites for this competition are the best placed ones, in this case, Real Madrid and Barcelona. But you can win a game and still lose the tie. Osasuna are very difficult at home.The Blaugrana will resume their season on January 3/4 with the first leg of the Copa del Rey clash against the Navarrans at Camp Nou.