Club owner Clive Palmer has thrown open the gates for free entry for the third versus fourth-placed fixture at Skilled Park and Mensink says that early indications are that a very strong crowd will be present on Sunday.
"If I am honest, and everything including the weather works out well on Sunday, then a sell-out would be perfect," he told the Gold Coast Bulletin.
"But I have to be a realist, so we will definitely get 10,000 fans there and we should have 20,000 by the end of the week."
A-League boss Lyall Gorman said the competition's hierarchy would be watching the crowd figure with curiosity.
"We are not living and dying by the crowd numbers at all, so we are not wedded to a certain number or target," he said. "We will just be watching it with interest."