In a series of quotes given to Catlan publication 'Sport', the Gremio boss hailed the starlet, tipping him for big things.
Barca hold a first option on the player, the fruit of many months of negotiation with the Brazilian side.
Portaluppi waxed lyrical of the playmaker's ability, saying that his quality was evident even in early training sessions. "I saw him training and I noticed that he had great quality. My job is to observ, but that is no use if a player doesn't have quality. What susrprised me was that nobody had seen his ability before me," he explained.
"I prepared him. I told him that he would have opportunities and when they came just to do exactly what he had been doing in training. I knew that when he played it would go well because of the wuality he has. He went out to play and performed even better than he had been doing in training. It wasn't a surprise to me because I knew that sooner or later when he got his chance he would grab it with both hands."
The Gremio boss way keen to outline what Arthur will bring to Barca, saying: "The same thing that Iniesta brings to BArca's forward. Obviously he's not at the same level yet, but their styles of play share a lot of similarities. Arthur is very good at getting away from his man and getting into attacking positions. He plays with his head up and that makes a big difference in football.
Finally, Portaluppi ended by tipping Arthur for big things. "He has a brilliant future ahead of him, not just for Barca but also for the national team. If he doesn't make the squad for this World Cup, you can be sure he'll be in the next one. When he moves to Europe he will develop even further," he concluded.