Gerard Pique does not think Barcelona or Real Madrid would have any chance of winning the Premier League in their first season if they were to play in England's top flight.
The Barca defender, 28, feels the level of adjustment would be too great for La Liga's big two, even though they have been dominant on the European stage in recent years.
Madrid won the Champions League in 2014 and Barcelona are the holders of the continent's elite club competition, but Pique, who played for Manchester United from 2004 to 2008, does not think the Spanish heavyweights could achieve immediate success if they played in England.
"I think that if Barcelona or Real Madrid goes to the Premier League then the first year of playing there, there is no chance of winning it," the Spain international told the Daily Telegraph.
"Yes, I think so, because if you go to Stoke, or other types of teams, then it will be really tough. It is a debate - we could spend hours on it.
"If Manchester United or Chelsea go to Spain then I say the same. No chance to win the league."
Spain host England in Alicante on Friday in an international friendly match ahead of Euro 2016 that will bring Pique into direct competition against his former United team-mate Wayne Rooney.
The experienced striker, captain for club and country, has come in for criticism for his performances this season, but the Barca star insisted the 30-year-old would still make the cut in his dream team of world stars.
Pique continued: "I have Wayne Rooney because he is one of the best English players in history.
"He needs to win an important title with England. It will be difficult, but you never know. Recently he became England's all-time record goal-scorer - a very important record. And he is not old - just 30.
"He is not as quick as he was, maybe, but he will always score goals - he scored a hat-trick against [Club] Brugge, he scored against CSKA Moscow. He has kept scoring.
"It is true he is getting older, we all have to accept that, but he has the ability to play for a long time. And when you don't score sometimes it is not because of you. Sometimes it is maybe the team is not creating chances for you.
"Not everything, always, is about your performance. It is about the team performance. When the team is not playing well then normally you will not play well. It is all about the team.
"Sometimes we have phone calls, texts. He is a fantastic lad. When I was there [at United] he was really young and I was really young too and he helped me a lot.
"He involved me in the team, helped me to learn English. He was the joker in the dressing room. I have great memories."