Spain manager Julen Lopetegui has insisted that defender Gerard Pique has responded positively to the criticism from fans in recent days.
The Barcelona centre-back has been an outspoken supporter of independence for Catalonia and was one of millions to participate in a referendum on the issue on Sunday.
The Spanish government had declared the vote illegal and ordered police to prevent Catalan citizens from participating, leading to ugly scenes of violence and widespread division around the country at large.
Lopetegui was forced to bring an early end to Spain's training session on Monday after supporters repeatedly heckled Pique, demanding that he step down from the national team.
"The behaviour of Gerard has been exceptional," Lopetegui told Cadena COPE. "I wanted to see how he was and I saw he was motivated and enthusiastic. He's well and fired up, if it were not like that he wouldn't be with me.
"It would have been an error to train behind closed doors. The fans have the right to express themselves.
"I know the situation is unpleasant, but I ask people for a little reason and sanity."
Pique has offered to retire from Spain duty if the Spanish Football Federation deem him to be "a problem".
Neil Wilkes
