As I'm obsessed with south American football I know quite a bit about Lucas Leiva. He is a very good player, but until last year he was playing in Serie B in Brasil. Granted it was with a Gremio side that should never have been relegated (incase you are unsure about Brasil domestic football, Gremio are quite a big club).
Not only that, he is moving to a game that is twice as fast as Brasilian football. I just hope Liverpool give the young guy time to develope & adapt to the English game. His arrival surely must mean Sissoko is leaving.?