The evolving Brisbane Roar have quickly moved to add spark to their attack after significantly bolstering their defence with the return of Socceroo Jade North.The Roar added a second new player at the start of the January transfer window on Wednesday by signing Africa-born livewire Julius Davies from Melbourne Victory.Davies, 18, had been unused by Ange Postecoglou at the Victory this season but new Roar coach Mike Mulvey believes the speedy midfielder can be the man to unlock the packed defences which have frustrated the defending champions.While the Roar have continued to dominate possession, they have struggled to score in losing eight of 15 games to be seventh on the A-League ladder."We've played against packed defences so what you need is players with the ability to open up the defence," said Mulvey, who talked-up Davies as a super-sub."Julius has a bit of X-factor about him."He's got the ability to break down defences and that's something that we've lacked in recent times."Born in Liberia and raised in Western Australia, jockey-sized Davies played with Bayern Munich U17s and 1899 Hoffenheim U19s before signing with the Victory last season when he played two matches under Jim Magilton."It was a team made up of a lot of big-name players and I was just a young boy," he said."I felt like I was going to play more this season but obviously that wasn't the case so I think this is a perfect opportunity for me to now establish myself."I'm very grateful for the chance and now I want to go out there and do a job."Davies' signing comes after the Roar released Rocky Visconte to join Western Sydney Wanderers, young Japanese defender Yuji Takahashi returned home and centre-back North signed on Tuesday night, leaving Japan's Consadole Sapporo.Mulvey would not comment on any further potential transfers, headlined by talk of a move for senior midfielder Erik Paartalu, but he admitted the new faces were part of the "rejuvenation process"."We definitely needed a defender there's no question about that and Jade fits that bill perfectly," he said."We're freshening up the squad a little bit."Brisbane Roar have been a championship-winning team the last two years but you can't rest on your laurels."It's evolution, that's what it is."