Putting ink to paper on Castro's contract is a big step towards Popovic realising his ambitions at Perth next season, but an even bigger step is Castro's new deal, which secures he joins Perth for pre-season.

The Spaniard previously had a clause that allowed him to join the squad just before the season's commencement, a subject that had caused much derision among Glory fans and had been blamed for the side's stuttering starts under Kenny Lowe.

"Firstly, I would like to thank everybody, my family too, for coming back here for another year," Castro said.

"A big part of my re-signing came after speaking with the coach. I want to learn as much as I can from Tony Popovic. 

"It's a new and exciting season for everybody. I think the goal is clear, we want to win trophies and I want to be a part of that in this new era."