Brisbane Roar defender Matt Smith is in doubt for tomorrow night's clash with Perth Glory.

The 28-year old Englishman had to be subbed off just before half-time of Saturday night's 1-1 draw with old club North Queensland Fury because of a lower back injury after he played every minute of every game prior to that this season.

Roar coach Ange Postecoglou confirmed that he wanted Smith at full fitness for Sunday's visit to Bluetongue Stadium to take on Central Coast Mariners so it was likely he would miss the home fixture with the Glory.

"If he's not 100 per cent we probably won't risk him because we've got a game on Sunday (against Central Coast)," Postecoglou said.

If Smith misses, Milan Susak will come into central defence to help marshal the best-performed back four in the league.