Messi, who is currently in Manchester ahead of Barcelona’s Champions League quarter-final against the Red Devils, is believed to be the star behind the Barca’s success streak at the Champions League about a decade ago.
Both Eto’o and Messi partnered in two Champions League finals, a 2-0 win in Rome 10 years ago and the 2011 win at Wembley.
These titles add to two more European honours and nine La Liga titles.
Messi was joined at Barcelona for five seasons by Eto’o, who scored 130 goals in nearly 200 appearances.
The Cameroonian striker now plays in the Middle East, with more than 350 goals in his career.
Speaking to beIN SPORTS, Eto’o said:
“I’ve said to Guardiola ‘you’ll apologise to me because it’ll be me that will make Barcelona win, not Lionel Messi’.
“It was a situation back then.
“Messi would come later but you can ask Xavi, Andres Iniesta and all the others.
“That was my era.
“It was me that made Barca win and Guardiola would ask me for forgiveness.”
The forward went on to criticise the Manchester City’s boss approach in his time with Barca.
“Pep Guardiola has lived his whole life in Barcelona.
“Messi would come later but you can ask Xavi, Andres Iniesta and all the others. That was my era.
“But in the years I spent there, he didn’t understand the squad.
“He didn’t live the life of our group.”
United fans will love these comments on Messi ahead of the game at Old Trafford.