Andres Iniesta told his Barcelona teammates to "be careful" as Lionel Messi made an astonishing impression during his early days with the senior squad.
Messi made his competitive debut aged 17 in October 2004 having earned a call-up to first-team training the previous year.
He would go on to score 672 senior goals across 17 trophy-laden years with the Blaugrana, establishing himself as the player many believe to be the greatest of all time.
However, prior to winning his glut of individual and team honours, Messi had to earn his stripes just like any other player emerging from the fabled La Masia academy.
It did not take him long to do so - and World Cup-winning defender Juliano Belletti can recall the ordeal of going up against the teenager in training.
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Belletti joined Barcelona from Villarreal in 2004 and he maintains he was in his "prime" having lifted the World Cup with Brazil two years earlier.
Yet he found he was no match for Messi, whom Iniesta warned him about prior to his first training session going toe to toe with the Argentine import.
"When I first trained against Messi, I had never heard of him," Belletti told GOAL. "Iniesta came and asked me if I knew who Messi was and Iniesta warned me to be careful because he is good.
"He said 'be careful' to me during the best time of my career. I was in my prime! But when he received the ball in training, he didn't care who he was playing against. It just happened to be me that time.
"The one-v-one, when I was even thinking about trying to tackle him, I found he had already beaten me. It was simply like that... I tried to kick him but I couldn't. I couldn't get him.
"It was definitely not a normal situation to see a player that good come from the academy and go straight into our team."
Messi made a total of nine appearances during his debut season, scoring once and picking up a La Liga winners' medal.
Belletti played a key role in the league-winning campaign but his role gradually diminished before he joined Chelsea, going on to win the Premier League once and FA Cup twice.
In contrast, Messi's importance for Barca only increased and he ascended to superstar status by helping Pep Guardiola win the continental treble during the 2008/09 season.
He won a total of 10 La Liga titles and four Champions Leagues before leaving Catalonia last summer to join Paris Saint-Germain on a free transfer.
