There was a QF82 on Saturday and Sunday in the last 7 days, as well as a QF81 on Sunday.The 81/82 is only scheduled for one day a week (82 on Thursdays and 81 on Fridays), when the AY A330 is in SIN for its weekly maintenance cycle.
What's interesting from FR24 is that QF291 on the 28th (Sunday) was assigned to be VH-EBR, and then the flight number changed to QF81.