Juventus manager Andrea Pirlo believes Lionel Messi's lacklustre form may be due to a "mental problem" after the summer’s dramatic fallout, during which Barcelona's greatest-ever player handed in a transfer request.
Messi, who had grown increasingly frustrated with the club's direction under former president Josep Maria Bartomeu, was dismayed by the treatment of his teammate and close friend Luis Suarez and the Argentine eventually attempted to invoke an exit clause in his contract. However, with a legal dispute looming, the 33-year-old was left with little option but to see out the final year of his deal.
Meanwhile, Barca's disastrous form - suffering a stunning 8-2 defeat by Bayern Munich in the Champions League - has carried over into this season under new manager Ronald Koeman. Defeat by Cadiz last Saturday left Barcelona languishing in ninth in La Liga - already 12 points behind leaders Atletico Madrid after just 10 games - while Messi has been short of his usual brilliance.
Asked about Messi's recent drop-off, Pirlo said: "He's in a special moment in his life, not his career. He had some problems in the summer, if he would stay at Barca or not, but during the game he's shown his value.
"More than in terms of football, maybe he has a mental problem, but I don't want to get involved. It's not to do with us. Messi is a phenomenon and he's proven that."
Asked about comparisons between Messi and Ronaldo, Pirlo said it would be impossible to compare the era-defining players.
The match will see Cristiano Ronaldo and Lionel Messi renew their rivalry on the pitch for the first time since the former's Real Madrid days.
"It would be a mistake to say one is better than the other," he said. "They've shared the Ballon d'Or in the last 15 years, it's not fair to say one or the other, they're two guys that have made millions and millions of fans enjoy themselves every time they play.
"We have to thank them for what they've done for the game."
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