However, the Senegalese winger went on to become one of Jurgen Klopp’s best signings at Anfield.
Mane left Southampton for the Reds, along with Virgil Van Dijk, but Austin felt the former would not fit in as much as the latter.
He said: "Van Dijk was there, Tadic was there, Graziano Pelle was there," before Tubes asked: "Could you tell Van Dijk then was s*** hot?"
Speaking to Tubes on the Golf Life podcast, Austin responded: "Yeah. To be the player he is, he had the potential (Van Dijk). But to go in there and see him day to day train, it was just effortless for him. It really was effortless and that was the thing. He needed to be pushed day in day out - and then if that come, then he was always going to go on to be the player that he has become. I truly believe that."
He went on: "Whereas Sadio, for argument's sake, when he moved to Liverpool I was thinking 'I'm not really sure here'.
"Honestly, I was not really sure. Bit raw to go and play for Liverpool, I'd seen it enough. There were glimpses, of course - he scored the hat trick against Man City and stuff like that. Brilliant. But then he went to Liverpool, and again I just think that comes with the management, the surroundings, the players you're playing with...he just took off and gone on to a completely different level again. You play with them top players, they just have something about them."