Carrasco worked with Yamal at Barcelona during the 2021/22 season, when the winger was just 14, and says his exceptional talent was obvious from the beginning.
Yamal has since developed into a key player for both Barcelona and Spain, and is now challenging Harry Kane and Kylian Mbappe for football's biggest individual honours.
The 19-year-old has scored 11 goals and provided seven assists in his last eight appearances for club and country. He also scored early in Spain's recent Nations League victories over England and Croatia.
Carrasco told SER Deportivos that Yamal's ability was clear from the moment he first saw him.
"Everyone who worked closely with Lamine knew he had a lot of potential, a lot of natural talent," Carrasco said.
"I think we haven't seen everything he's capable of yet.
"He's still very young, he has a lot to prove, even though he's already leading a team as important as FC Barcelona and the Spanish national team, at just 18 or 19 years old. We still have a lot to see."
Yamal is also chasing major honours at club and individual level, with Carrasco believing it is only a matter of time before the Champions League and Ballon d'Or are added to his collection.
Carrasco also pointed to the improvement in Yamal's numbers this season after a less productive La Liga campaign last term.
"Maybe last season he didn't have the best numbers in the regular league, but he's still in his breakout phase," he said.
"This season's numbers are already better than last season's."
Yamal's confidence has attracted plenty of attention, particularly after he said recently that he deserved to win the Ballon d'Or ahead of Kane and Mbappe.
Carrasco, however, does not see the youngster's outspoken personality as a problem.
"He's sincere, honest. He's a person with a very strong character," he said.
"He knows the talent he has, that he's in the top one or top two in the world, and he says so openly.
"He's not the type of footballer that people generally accept most readily, a humble footballer like Iniesta or Messi, but this is his way of being."
Yamal will have another chance to impress when Spain face the Czech Republic in the Nations League on Saturday, October 3, while Barcelona's next match is against Getafe on October 10.
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