Boss Paul Merson knows the player from his time at Portsmouth. Larossa really impressed Merson during that spell and he hopes he has unearthed a gem.
"I remember this lad coming to Portsmouth. It takes a lot to impress me - but he did," said Merson.
"He was quite special but the problem at the time was that he could not get a work permit.
"If we see the same player we did at Portsmouth, then we might have a real talent on our hands."