Cox was handed a lifeline by Fremantle after being axed by Collingwood at the end of last season, and the 35-year-old will be thrust in for the derby as a replacement for Sean Darcy (concussion).
Fremantle coach Justin Longmuir confirmed the news on Friday, with the Dockers to unleash a two-pronged ruck attack featuring Cox and Luke Jackson.
Cox played 139 games for Collingwood across 10 seasons, including the club's premiership in 2023.
The 211cm American is known for his swagger and brashness, and they are traits Longmuir has encouraged Cox to continue at Fremantle.
"We want him to be himself, and want him to bring all of himself," Longmuir said.
"He's done that since he got to the club. He's done it at training sessions, in the gym.
"So we wouldn't ask him to not do that on game day."
Cox has averaged 39.5 hitouts, six marks and 21.5 possessions across his two WAFL hitouts this season.
But with Darcy ahead of him in the pecking order, Cox has been forced to wait patiently.
Star midfielder Hayden Young has also been named after overcoming a strain to his left hamstring.
"He's been our best player at Peel so far in two games, and really he's been just waiting for an opportunity," Longmuir said.
"My message to him the last three, four weeks was just make sure when the opportunity comes up, you're in good form, and he's done that."
Young has a recent history of soft tissue injuries, most notably undergoing surgery on his right hamstring last year, but Longmuir is keen to persist with the 25-year-old in the midfield, along with short stints in attack.
"Although his minutes might slightly change first week back in terms of forward-mid balance, he'll continue to play the same role," Longmuir said.
"He's one of our best centre bounce players, so we want him in a position where he can best impact the game.
"And we feel like we're on top of his injuries, and feel like he's had a really good rehab stint."
Forward Michael Fredrick will also return after overcoming an ankle injury, but Jaeger O'Meara is set for an extended stint on the sidelines after suffering facial fractures at training this week.
"He's a much loved teammate. To see him go down to training, it spooked us a little bit," Longmuir said.
West Coast (2-3) will be without midfielder Deven Robertson (ACL) for the rest of the season, while Jack Graham has been booked in for shoulder surgery and will miss about two months.
14°C