Xavi Hernandez says his former Barcelona colleague Lionel Messi's decision to quit international football with Argentina must be respected.
Messi, 29, announced his retirement from the national team after he missed a penalty during a shootout defeat to Chile in last month's Copa America Centenario final, in what was a third consecutive loss in a major final for La Albiceleste.
The announcement has shocked world and Argentine football, with Argentina legend Diego Maradona and national president Mauricio Macri among those calling on Messi to reconsider.
The situation is complicated by chaos at the Argentine FA, with national coach Gerardo Martino resigning this week and the country's participation in the upcoming Olympic football tournament also in doubt.
Xavi told AS that Messi had "suffered tremendous frustration" with Argentina through recent years and had earned the right to decide whether or not he played again for the team.
"You must respect what he decides," Xavi said. "He could return to his national team next week if he wants to. He is the best in the world, and in history. We have to put ourselves in his situation. Leo is one of a generation of Argentina players who have suffered tremendous frustration.
"They don't win anything -- despite being so close all the time. They lost the final of the World Cup in extra-time and then two Copa America finals in a row [on penalties]. Messi has an Olympic gold medal and an Under 20 World Cup. We [Spain] won two Euros finals we played, the World Cup, the Champions League..."
Xavi said that Messi was actually a straightforward character, who sometimes got angry with situations. But that if you succeeded in keeping him happy, then your team was always going to do well.
"He is a guy who is direct, trustworthy," he said. "He gets angry, as we all have. You must keep him happy. When that happens, Barca are close to success. He makes the difference in every game, in a collective sport. Every year he is better and he has looked after himself in every sense."
Xavi was also asked about the latest big hope to emerge from Barca's La Masia academy -- 19-year-old midfielder Carles Alena, who is set to do preseason with the first team this summer.
"I know him," he responded. "Left-footer, attacking midfielder and he can succeed at Barca. He is among those who are called to make the first team. To make that step for kids it is about mentality. For Alena it is all in his head. If he sticks with it, he will arrive and follow [Sergio] Busquets and Pedro [Rodriguez]."
Xavi said that last summer's signing, Arda Turan, who had to sit out the first half of the 2015-16 campaign and then struggled when able to play, still has time to come good.
"[Arda] needs time," he said. "If things change this year and he has a good season, he will be an important player. He has now realised how hard it is to be a Barca player. Barca is the final exam for a player."