Athletic Bilbao midfielder Ander Herrera has highlighted Brazil and Team GB as major threats to Spain's bid for Olympic gold this summer.
The world and European champions are looking to add the Olympic football title to their list of honours 20 years after their only previous success at the Games in Barcelona, but Herrera is aware that there are a number of strong sides capable of challenging for medals.
He told Marca: "The objective is to start well and play well. To win a medal would be fantastic and the gold would be incredible, especially given how long it has been since Spain has been at the Games.
"However, we always respect the opponents because at this level anyone can cause you problems.
"Brazil is the favourite and Great Britain as hosts and with the team they have are too. Then there is Mexico, Uruguay, the African sides...we want to be in this group (of favourites) but we have to win on the pitch."
Atletico Madrid striker Adrian Lopez echoed those thoughts, saying: "These competitions are always difficult. Great Britain, Brazil, Uruguay and Mexico could be the strongest, but then there are always teams that you don't know very well that are physically very strong and are difficult to judge.
"An example is Japan, who are in our group, and they could surprise you. We have to prepare for every game as if they were finals."
Adrian could consider himself slightly unfortunate not to make the final squad that went to the Euros after scoring on his senior international debut against Serbia just before Vicente Del Bosque named the 23 men he was taking to Poland and Ukraine.
However, the 24-year-old is now looking forward to being one of the senior figures in the Olympic squad, adding his experience to that of Euro 2012 winners Juan Mata, Javi Martinez and Jordi Alba.
He said: "I don't have pressure being one of the over-age players in the team, I take it as a responsibility. We have to help the young players with our experience and, above all, Mata, Javi Martinez and Alba can help with what they have lived in the past few weeks."
