It's the only change to the side that narrowly lost to Fremantle last week.
"It's purely a match-up based decision, Cam O'Shea was incredibly unlucky not to play last week," senior coach Ken Hinkley told portadelaidefc.com.au earlier on Thursday.
"But we knew we perhaps needed a small defender in the side to go against Ballantyne or Walters and with that in mind we gave Jarman that opportunity.
"This week we'll bring Cam back into the side."
One player who won't travel with the Tigers to Adelaide will be reigning Richmond best and fairest Daniel Jackson, who today announced his retirement from AFL football effective immediately.
Both Richmond and Port Adelaide will confirm their final 22-man teams at 4:30pm on Friday afternoon.
