Brisbane Roar's A-League Men finals hopes have taken a hit with star recruit Robbie Kruse undergoing knee surgery.

The former Socceroos winger - who has yet to spend much time on the field for the Roar - will miss Saturday's home clash against Western United at Redcliffe, with his availability for the rest of the season in doubt.

"Robbie unfortunately has gone in for an op on his knee," coach Nick Green said.

"We are missing Robbie this weekend."

When asked what kind of injury it was, Green said: "We are just waiting to find out post-op what the details are. It is not too good for Robbie at the moment."

Roar captain Tom Aldred said Kruse's absence was a huge loss.

"We were very hopeful when we got him in the door that he could produce because he was playing up against me every day at training and he was brilliant," Aldred said.

"It is just unfortunate that he's got to get that (knee) corrected because he was so close to being at his best."

The Roar are on 20 points, seven points outside the top six as the season approaches its climax.

Western United are on a roll after three wins in a row and sit seventh on 25 points.

"Everybody is striving for consistency," Green said.

"They have been on a fantastic run and it goes without saying that if you get a couple of wins your confidence grows again and anything is possible.

"Anybody on the day can beat anybody. We have prepared well this week and we understand what is coming.

"We want to cause problems for them and get that win on the board that has been missing for a couple of weeks."

Roar forward Carlo Armiento will celebrate his 50th A-League game against Western United while defender Scott Neville is out suspended.

Aldred wore a purple kit for the club's pre-game media obligations, which they will take the field in on Saturday in support of Epilepsy Queensland.

"We are well aware with six games to go we need to go on a purple patch and win back-to-back games," he said.