Brisbane Roar's attacking stocks have been further decimated with young gun Brandon Borrello set to move to Europe next season.

The 21-year-old is understood to have signed for a second division club in Germany, making Wednesday night's AFC Champions League dead rubber against Ulsan Hyundai his final match for the Roar.

The unknown club has triggered Borrello's buyout clause, allowing him to make the shift despite being under contract for one more season.

Originally from Adelaide, Borrello made 75 A-League appearances for the Roar across four seasons, scoring 13 goals.

His agent John Grimaud has overseen previous transfers of Australian players to German clubs, including Robbie Kruse, Mitch Langerak and Mathew Leckie.

While it has netted the Roar a reasonable transfer fee as reward for nurturing the explosive young winger, it means coach John Aloisi will field an entirely different front three next season, with his other first-choice options Jamie Maclaren and Thomas Broich also leaving.

Maclaren and Borrello are both in line to start against Ulsan but Broich, 36, will not be involved at all.

The dual Johnny Warren medallist ruled himself out of the clash due to concerns over his ankle, even though the Roar's medical staff had reportedly cleared him to play.

"I rocked up to training still hoping that I'd be alright but it's just too painful at the moment. There's no reason to push it now," Broich told News Corp Australia on Monday.

Broich will still be at Suncorp Stadium to say goodbye to fans before embarking on the final chapter of his playing career, most likely overseas.

Maclaren, meanwhile, is poised to make a decision on his future in the next week or so, with continental Europe - not the UK - his likely destination.