Lionel Messi was always showing signs he was headed for greatness from the days he rotated between Barcelona's B side and the first team and his legacy will be impossible to surpass, says Samuel Eto'o.

Former Cameroon striker Eto'o was a team-mate of Argentina great Messi from 2004 until he departed for Inter in July 2009 as part of the deal that took Zlatan Ibrahimovic to Camp Nou.

Eto'o was part of a devastating Barca attack that also included Thierry Henry and Ronaldinho and he won three LaLiga titles, two Champions Leagues and a Copa del Rey at Camp Nou.

The 39-year-old had a first-hand view of Messi's development from raw talent to world superstar and said it was a matter of time before he became one of the best on the planet.

Speaking courtesy of LaLiga, Eto'o said: "He would move between the B team and the first team, and he was very good.

"We already knew back then that Messi would one day be what he's become. I'm very happy because he's achieved that through his own hard work."

Eto'o says one of the most pleasing aspects of Messi's success is the way he has managed to stay grounded during a sensational career that has seen him become a six-time Ballon d'Or winner and doubts any player can better his achievements.

"He hasn't changed at all. He's still the good person that I knew back then and that I still know," he added.

"He recently said 'thanks to Samuel', thanks to my advice – that I won't reveal here – that his career changed. 

"Back then he had to iron out a few things but he's always had that talent. I'm proud and happy to see the story that he's written and that hasn't ended yet.

"It's going to be very difficult, impossible even, to surpass his legacy.

"The most important thing for me is his character. Everyone appreciates him, adores him as a player.

"But he's a wonderful guy and I'm proud to still be among his friends."