Catalonia’s government is determined to hold a vote on October 1 on breaking away from Spain, despite warnings they are breaking the law.
The referendum is deemed illegal by the Spanish government and the country’s Constitutional Court.
And while Manchester City manager Pep Guardiola previously declared his support for the vote, Spanish national Rafael Nadal has raised his concerns on breaking up the country.
He told El Mundo: “I think what is happening on October 1 ought not to take place because, from my point of view, everyone should respect the law.
“The laws are what they are and one can’t skip the laws because you want to skip them. I can’t run a red light because that traffic light doesn’t seem right to me.”
The 31-year-old, who just won his 16th Grand Slam at the US Open on Sunday, is considered a national hero.
He grew up and lives on the Balearic island of Mallorca, and this year the centre court at Barcelona’s Royal Tennis Club was renamed the Rafael Nadal Court.
But the Spaniard is also a Catalan speaker, ash says he feels “very close” to both Catalonia and to Spain.
He added: “I don’t understand Spain without Catalonia. I don’t want to understand or see it.
“I believe that together we ought to be able to understand each other and I think we have to make an effort to reach an understanding because I think we are, without any doubt, stronger together than separated.
“Spain is better with Catalonia and Catalonia is better with Spain from my point of view.”
The referendum, which was approved in the regional parliament, has been suspended by Spain’s constitutional court.
But Catalan leaders have vowed to hold it regardless.
At a demonstration in the Catalan capital Barcelona in June, former Barcelona manager Guardiola made a rallying cry in favour of the split.
He said: “We will vote, even if the Spanish state doesn’t want it. There is no other way.”
In his speech in June, Guardiola also appealed to the international community and “democrats the world over” to support Catalans’ “right of freedom of expression and the right to vote”.