The match will be Roberts' final at Melbourne's home ground, with the playmaker signed to join UK Super League club Castleford.
The 29-year-old spent six years with the Bulldogs from 2006 before a stint at Parramatta and then finding a new home with Melbourne this season.
Canterbury go into the match with a big question mark over their form after only winning two of their previous eight matches but Roberts said the Bulldogs wouldn't simply roll over.
The Bulldogs crashed out of last year's NRL finals in the corresponding game, outclassed by Newcastle. The Knights then eliminated Melbourne the following week.
"You can't really take their form into the finals because it's a different competition.
"They've got two great halves there in Josh Reynolds and Trent Hodkinson who have had a great season and who we'll have to look out for."
Tagged as erratic through his career, Roberts has been playing the most consistent football of his career this season.
"I honestly think I've learnt so much in one year playing alongside Cooper Cronk and that was one thing that was appealing to me when I came to the club.
"It might be my last game with the Storm but I'd like to stay for a few more weeks if possible," he said.
- AAP