Brisbane Roar's two key signings in the past month loom as integral to their A-League Men finals hopes, with Keegan Jelacic and Marco Rojas set to line up against Melbourne City

The Roar signed 21-year-old Jelacic on loan from Belgian club Gent a month ago, then picked up ALM veteran Marco Rojas last week following his six-month sabbatical from the game after playing for Chile's Colo Colo.

The attacking duo played crucial roles in the 1-1 draw with Wellington last week in what was Jelacic's first start and the club debut for Rojas, who came on in the second half.

Acting Roar head coach Ruben Zadkovich said the pair had added class and would be vital again against City at Suncorp Stadium on Saturday night.

"I'd like to think that everyone can see the difference they make in terms of their footballing ability and technical ability," he said.

"Marco has not played for a long time so it was nice to get him back on the pitch.

"I thought he brought the crowd into it through his experience and quality on the ball.

"Keegan is a little bit similar and had (two weeks suspended) which was a bit of disruption to his load and how he was going, but all things considered they played really well and played their part in that comeback."

Former Perth Glory coach Zadkovich is familiar with both players for different reasons.

"I had Keegan for 19 or 20 starts last year at Perth where he was outstanding. He is an unbelievable talent," he said.

"His moments of quality late in the game show his physical and technical capabilities and how composed he is under pressure.

"I have known Marco a long time and played against him. He has embarrassed me a few times on the pitch so I know how hard he is to play against. I think he is a fantastic addition."

Zadkovich said he had learned in his fortnight at the ninth-placed Roar that there were "a lot of good people" on board who were working hard to guide the club through a difficult time after former head coach Ben Cahn took indefinite sick leave.

He said he expected sixth-placed Melbourne City to come out firing after their disappointing loss to Perth last week but insisted Brisbane could beat any ALM rival if they played to their potential.