The Glasgow skipper will clash with the Aussie hardman at Firhill when the Warriors go into battle with the struggling Irish giants.
But Al says that no matter what takes place on the field of play the pair will still be friends when the dust has settled.
He told the Daily Record: "We have been going at each other for years and I am sure this tussle will be every bit as heated.
"Apart from the obvious physical challenge in the line-out there will be a lot of verbals and it is always great fun.
"But when the final whistle sounds we will be pals again. Justin is a terrific lad and you can appreciate why he has become such a cult figure in Belfast."
Andy Henderson is also looking forward to a clash with World Cup midfield partner Rob Dewey, making his return to Scotland after a summer switch from Edinburgh.
The centre said: "The pair of us know each other's game inside out but I am sure there will be a bit extra in terms of intensity and edge.
"Whether that is a good thing or not remains to be seen - we'll just have to wait to see how the match flows. Whatever happens, it will be a testing challenge for both of us."