A-League leaders Brisbane Roar have slumped to back-to-back defeats for the first time this season following the 1-0 loss to Melbourne Heart at AAMI Park.

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Roar, who went down 1-0 at home to Newcastle Jets last weekend, fell behind to an Orlando Engelaar goal just after the hour mark.

Mate Dugandzic capitalised on an error from midfielder Luke Brattan before playing in the Dutch veteran to open the scoring.

Heart could have doubled their advantage 15 minutes later, only for the unmarked Nick Kalmar to head over the bar from close range.

Thomas Broich almost restored parity by firing narrowly wide of the mark, but the hosts held on to inflict a second-straight defeat on high-flying Brisbane, who remain at the summit of Australia's top flight.