"These moves are always a gamble but I think this is a good one," said Vickery.
"Lucas has two full seasons behind him - one helping Gremio win promotion from the second division and then last year's success when he was chosen as the player of the championship.
"He's an exciting player of a type Brazilian football hasn't produced too many of recently.
"Of late their central midfielders have tended to be 'holders' who sit and allow the full-backs to push forward. Lucas is different. He's a big, blonde figure whose power and physical strength comes with attacking ability.
"He can pass well and loves to rumble forward. He gets on the scoresheet both with blistering shots from range and from bursting beyond the strikers. You can certainly imagine him playing alongside Javier Mascherano, for example."