Pettybourne moved to Wests Tigers in the last off-season and has since impressed fans with his hard running style, which is sure to be on show against a huge South Sydney forward pack.
Pettybourne told Wests Tigers TV he was up for the challenge of facing the Rabbitohs forwards who include the giant Burgess brother, Sam and George.
"This is a chance for us to step up a gear," said Pettybourne.
"They're big, strong and fast. We've got the players here that can do the job as well.
"They've got two arms, we've got two arms. They've got two legs, we've got two legs.
"We've just got to run hard and play well.
"If we can step up this week, anything can happen."