'Possum Up A Tree'

Went for a walk around the Botanical Gardens at lunchtime today, took a few photos, but heading back to my car once I'd left the gardens I heard some strange noises and looked around, spotted this guy up a tree and he / she was sitting on another possum who seemed to be making some noises of being very uncomfortable. Not sure what was going on up there and it was very unusual to see possums in the middle of the day as they are nocturnal.
Not sure whether this one is a brushtail or a ringtail, somebody might be able to identify it for me?

I managed to get a pair of tickets to Friday nights first match of the AFL final series where the Hawks take on the Sydney Swans once again, but this time on our own home turf at the MCG. Just myself and Dylan will be going as it's on too late for our little possum to stay up.