Nadal backs Argentina to respond after Saudi shock
"I'm not one for extremes, neither too much euphoria nor too much catastrophe," Spaniard Nadal, a big football fan who supports Real Madrid, said before his exhibition match against Norwegian Casper Ruud in Buenos Aires.
"The world hasn't changed...They simply lost a game and there are two to go. The least they deserve is confidence and respect.
"They come from being champions of America, from having one of the best winning streaks in history, so why lose confidence? I still think Argentina is a clear candidate to go far."
Nadal, who won two Grand Slams in an injury-hit 2022, said Saudi Arabia's victory was merely a reflection of just how evenly matched soccer has become.
He also paid tribute to Messi, who played for Real's arch-rivals Barcelona.
"Messi took things away from Real for years but in the end, as a sports lover, you appreciate someone so special," Nadal said. "In LaLiga we've been lucky enough to enjoy him in the best years of his sporting career.
"He has given us special moments in the world of sport, he's one of the top players in the history of football and sport".
Argentina play Mexico in their second Group C match on Saturday.