No one can fill the big shoes left behind by Matt McKay but young gun James Donachie may yet wear the former Brisbane Roar captain's No.15 jersey after signing with the two-time reigning A-League champions for three seasons.

Two-time National Youth League Player of the Year Donachie, 19, has been snapped up on a long-term deal, capping the good work that earned him an A-League debut in the final regular season round of 2011-12 against Gold Coast United.

The central defender admits he has much to learn but obviously loves a challenge judging by the jersey choice he is contemplating.

Given the options of striker Kofi Danning's No.9, McKay's No.15 or fellow defender Matt Mundy's 12, Donachie aimed high.

"I was thinking more along the lines of 15. I think it has a nice feel to it," he said.

McKay may have moved on to South Korean club Busan IPark but Donachie said there was still plenty of experience at the Roar to help him follow in the Socceroos midfielder's footsteps.

"Choosing to stay here was an easy choice, especially with the experience of Matt (Smith), Stef (Shane Stefanutto) and Jurms (Matt Jurman), it will definitely help me out in the long run," he said.

"After I played the Gold Coast game, I just wanted to keep playing with the senior boys so I can't wait to have that opportunity again."