Brisbane Roar’s defeat to Adelaide United has gone from bad to worse with news captain Matt McKay could miss more than six weeks with a knee injury.

The 34-year-old was withdrawn early in the second half after hobbling away from a seemingly innocuous midfield collision.

“Matty I think is out for at least six weeks with his medial,” Roar coach John Aloisi said.

“That’s something we have to deal with but it’s unlucky for Matty because he’s been brilliant for us all season and he’s our leader.”

McKay's injury further sours an already forgettable afternoon for Roar after they walked away from Coopers Stadium without a point having looked on course for all three.

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Aloisi’s side seemed certain to run over the top of Adelaide when Marcelo Carrusca was dismissed in the 82nd minute but instead they were left empty handed following Sergio Cirio’s stoppage time penalty.

“They scored off a set piece and in the final third we lacked a little bit in terms of finding that final pass,” the Brisbane boss said.

“Second half we were just all over them.

“We got the goal we deserved and we thought we were going to go get three points because we were trying our best to win the football game.

“But it wasn’t to be and we now have to now move on and make sure everyone is ready for the next game at home.”