Gatti spent the majority of his career with Boca Juniors, and only retired in 1988 after making his debut in 1962.
"He [Messi] is some way away from the players I saw," Gatti told El Chiringuito de Jugones. "And doesn't even get into the top echelon.
"The best in my lifetime was Pele, then Alfredo Di Stefano. The rest are further back, and even Ronaldinho, as his best, was better than Messi.
"I was at Boca and Argentina with Maradona. Diego is better. No discussion. Messi isn't better than him.
"And in addition, Diego cane alive with big moments, in important matches. Messi hasn't."